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Blackberry Mousse Cake

I’m partnering with Oregon Berries to make this absolutely delicious blackberry mousse cake!

It’s made with tender blackberry swirled cake layers, the fluffiest blackberry mousse filling, and blackberry buttercream frosting.

It’s truly bursting with Oregon blackberries and tastes just like sunshine!

image of a blackberry mousse cake that's been cut and a slice has been plated showing it's delicious filling

I love using fresh blackberries when they’re in season, but to be totally honest I use frozen berries the rest of the year.

Oregon blackberries are naturally ripened, picked at peak ripeness and flash frozen within 24 hours of being picked. This locks in all their delicious flavor and means that frozen berries are just as wonderful to bake with as fresh berries.

As an added bonus, frozen berries have a longer shelf life and are actually a better value compared to fresh berries. It’s truly a win-win situation!

How to Make This Blackberry Mousse Cake

To make sure your blackberry mousse layer cake turns out as amazing as possible, let’s walk through each step together!

I’ve also included a video tutorial of the process below.

Step 1: Make the Blackberry Mousse

Make the blackberry mousse first so it has time to chill. It can also be made 1-2 days ahead of time.

Melt the white chocolate by placing it in a medium-sized, heat-proof bowl with heavy cream.

Microwave for 45-60 seconds, then let the mixture sit for a minute and stir until combined using a rubber spatula. This can also be done in a double boiler.

Then stir blackberry jam into the white chocolate mixture. If desired, add a small squirt of purple gel food coloring to give this mousse a more vibrant purple color.

image of white chocolate ganache being mixed together with blackberry jam

Mix thoroughly until the mixture is smooth and there are no clumps of jam. Set aside.

Next, add the heavy cream, powdered sugar, vanilla extract, and a pinch of fine salt into a large bowl or the bowl of a stand mixer fit with a whisk attachment.

Mix on medium-high speed until the whipped cream starts to gather in the whisk attachment and you can see texture around the edges of the bowl (see photo below).

At this stage, the whipped cream should be thick and able to keep its shape.

image of whipped cream being made in a stand mixer

This usually takes about one to two minutes in my stand mixer.

Gently fold the whipped cream into the blackberry white chocolate mixture in two additions.

image of whipped cream being folded into blackberry ganache

Use a rubber spatula to swoop around the sides of the bowl and pull through the center.

Be careful not to over-mix the mousse, or it will become deflated and lose its structure.

Cover the mousse with plastic wrap and chill in the refrigerator for at least 2 hours.

image of blackberry mousse being covered with plastic wrap before being place din the fridge to set

Make sure you keep the mousse chilled until right before you fill the cake because it can also lose its shape if it gets warm.

Step 2: Bake and Level the Blackberry Swirled Cake Layers

Next, make the blackberry swirl and vanilla cake batter following the recipe card at the bottom of this post.

image of an 8 inch cake pan being filled with fluffy white cake batter to make a strawberry mousse cake

Pour half of the batter evenly between the prepared cake pans. I added about 275g of batter per pan.

Drizzle 1/2 cup of blackberry jam over the cake batter. I put my jam in a piping bag to make it easier to drizzle, but you can also use a spoon.

Use a small offset spatula or butter knife to swirl the blackberry jam into the cake batter.

image of blackberry jam being swirled into vanilla cake batter to make blackberry swirled cake layers for a blackberry mousse cake

Top with the remaining batter, adding another 275g of batter to each pan.

Smooth the batter with a spatula or small offset spatula so that it’s even across the pan.

image of vanilla cake batter being smoothed into an 8-inch cake pan

Bake for 32-35 minutes or until a toothpick comes out with a few moist crumbs.

Remove the cake layers from the oven and let them cool in the pans for about 10 minutes.

Gently run an offset spatula around the rim of the cake pans to loosen them, then flip them into wire racks to finish cooling.

Once the cake layers have cooled to room temperature, use a serrated knife to level the top of each cake layer.

image of a vanilla blackberry swirled vanilla cake layer being leveled with a serrated knife

It makes the cake so much easier to stack and assemble!!

If you’re making these in advance, you can wrap and freeze them at this point.

Step 3: Make the Blackberry Buttercream

While the cake layers bake and cool, make the blackberry American buttercream.

I like to use American buttercream because I think it’s the easiest to make and I love eating it. However, it is quite sweet!

If you want to use a less sweet frosting, I’d recommend making a batch of my Swiss meringue buttercream or my hybrid buttercream.

image of blackberry buttercream frosting being mixed together in a large glass bowl

This frosting can also be made in advance if needed and kept in the fridge for up to a month!

If your frosting seems too thick after mixing your ingredients, add in additional cream (1 tablespoon at a time).

Or if the frosting is too thin, add in more powdered sugar (quarter of a cup at a time).

If you’re unsure how thick your frosting should be, you can learn what consistency you’re looking for in my frosting consistency post.

Step 4: Stack and Fill the Cake Layers

Stack and frost the cake layers on a greaseproof cake board using a dab of blackberry buttercream to help stick the first cake layer to the board.

Pipe a double ring of the purple blackberry buttercream around the perimeter of each cake layer.

image of blackberry jam being smoothed onto a vanilla cake layers inside a ring of buttercream frosting

Spread 1/4 cup of blackberry jam inside the frosting ring, then top it with an even layer of blackberry mousse. Use about 1/2 of the mousse between each layer.

Then gently press blackberries into the mousse.

image of blackberries being pressed into blackberry mousse cake filling as a layer cake is being stacked

Chill the cake in the freezer for about 10 minutes, then repeat with the next cake layer. This helps lock the filling in place and prevents the layers from sliding around as you frost the cake.

Once all the cake layers are stacked, spread a thin coat of frosting around the cake to fully cover the cake layers.

If your layers are sliding around, insert a chopstick or wooden dowel into the center of the cake to make it more stable.

Smooth the frosting around the cake with a bench scraper, then chill the cake for about 10 minutes in the freezer.

image of a blackberry mousse cake being crumb coated with blackberry frosting

This will help the filling between the cake layers firm up and make the cake way easier to frost.

Step 5: Decorate This Blackberry Mousse Cake

Add a second, thicker layer of purple blackberry frosting to the cake and smooth using a bench scraper.

image of blackberry buttercream being smoothed onto a blackberry mousse cake with a bench scraper

Pipe swirls of the different colors of buttercream in a curved line around the side of the cake and up on top of the cake like in the pictures above.

Start with the pink buttercream and pipe large buttercream rosettes, then gently press some fresh blackberries into place.

image of a fresh blackberry being pressed into buttercream swirls to decorate a blackberry mousse cake

Fill in the gaps with swirls and dollops of the other colors of buttercream, then enjoy!

image of a beautiful blackberry mousse cake that's been decorated with buttercream swirls and fresh berries

Substitutions & Swaps: Blackberry Swirled Cake Layers

While I love this recipe just the way it is, I know some of you might not have all these ingredients on hand.

Below are some swaps and substitutions that can be made in this recipe:

  • Cake Flour – This recipe turns out best with cake flour. If you can’t find cake flour, you can make your own makeshift cake flour using this method. You can also swap in a good gluten free flour blend (like this) if needed. Just be sure to stir the batter longer than normal to help give the cake proper structure, and let the batter sit for about 20 minutes before baking it if you opt to make a gluten free version.
  • Granulated Sugar – I do not recommend reducing the amount of sugar or changing the type of sugar, as it will change the texture of the cake layers.
  • Sour Cream – You can also use full fat yogurt, buttermilk, whole milk, or an alternative yogurt or milk (almond, soy, oat).
  • Vegetable Oil – Use any flavorless oil in this recipe. Canola, vegetable, or even sunflower oil would all work great. I don’t recommend olive oil though, as it has a strong flavor and will change the taste of the cake.
  • Egg whites – This recipe uses large egg whites. I like to use the type that come in a carton so that I don’t have to separate my eggs, but you can also use fresh egg whites. If you have an egg allergy you can try using a vegan egg replacer. You can also use 5 large, whole eggs but they will change the texture of the cake layers a bit.
image of a blackberry mousse cake that's been cut into to show its blackberry swirled cake layers, blackberry mousse filling, and blackberry buttercream frosting

Substitutions & Swaps: Blackberry Buttercream & Mousse

Some swaps and substitutions that can be made in this frosting recipe include:

  • Unsalted Butter – If you only have salted butter on hand, you can use it in place of the unsalted butter. Just be sure to omit the salt that this frosting recipe calls for. You can also use vegan butter in its place!
  • Heavy Cream – Coconut cream can be used in place of the heavy cream as a dairy-free alternative.
  • White Chocolate – You can use white chocolate chips or good-quality white chocolate bars to make the blackberry mousse.
  • Blackberry Jam – I love using my blackberry freezer jam in this recipe, but any seedless blackberry jam or jelly made with Oregon blackberries should work great!
image of a bite of blackberry mousse cake on a fork

Making This Cake in Different Sizes

I used 8″ cake pans to make this cake, but this recipe can be used to make different sized cakes. You can also half or double the ingredients to make a half or double batch!

You can make four 7″ or 6″ cake layers with one batch of batter. Bake the cake layers at 350 F / 175 C for 34-37 minutes or until a toothpick comes out with a few moist crumbs.

One batch of batter can also be used to make one 9×13-inch sheet cake. Bake it at 350 F for 40-50 minutes and use flower nails or heating cores to help the cake bake evenly.

You can also use this recipe to make a Bundt cake! Bake time can vary based on the size and type of pan you use and can take anywhere from 45-75 minutes. I recommend using a toothpick to test for doneness and checking on it every 5-10 minutes once it’s been in the oven for 45 minutes.

The final variation of this recipe is cupcakes!! This recipe makes about 36 regular sized cupcakes. Fill 3/4 full and bake for 17-19 minutes or until a toothpick comes out with a few moist crumbs.

Tips for Making the Best Blackberry Mousse Cake

  • When making the blackberry mousse, chill your mixing bowl and whisk attachment in the freezer. It makes it easier and quicker to whip up the whipped cream for the mousse.
  • Properly measure your flour (spoon into the cup measure, then level). Or better yet, use a kitchen scale to measure your dry ingredients.
  • Mix the cake batter just until the ingredients are incorporated once you add in the flour. This will ensure your cake layers are tender and fluffy.
  • Use a scale to weigh your cake pans as you fill them. It will make your cake layers bake to the same height and bake more evenly.
  • Bang your cake pans on the counter before putting them in the oven. This brings any big air bubbles that are trapped in the batter to the surface.
  • Level your room temperature or thawed cake layers with a serrated knife to make them easier to stack.
  • Chill your cake layers in the freezer for about 20 minutes before assembling the cake. It makes it so much easier to stack and frost them!
image of a slice of blackberry cake that's been cut into with a fork

Making This Cake in Advance and Storage Tips

Make your cake layers in advance and freeze them. It breaks the process up and makes it more approachable.

The blackberry mousse can also be made in advance! Make it up to 2 days in advance and store in the fridge.

Make the blackberry frosting ahead of time or save any leftover frosting. Store in an airtight container in the fridge for up to a month.

This frosting can also be stored in the freezer for up to 3 months! Just be sure to give it a good stir once it thaws to make it nice and smooth again. This cake can last in the fridge for up to 2 days.

image of a slice of blackberry cake that's been cut into with a fork

Let Me Know What You Think

If you try this cake recipe, I’d love to hear what you think! Please leave a comment and rating below.

And don’t forget to tag us @chelsweets and @oregonberries so that we can see your delicious creations on social media!

Other Recipes You Might Like:

Yield: 24

Blackberry Mousse Cake

image of a blackberry mousse cake that's been cut and a slice has been plated showing it's delicious filling

This blackberry mousse cake is made with tender blackberry swirled cake layers, the fluffiest blackberry mousse filling, and blackberry buttercream frosting.

Prep Time 30 minutes
Cook Time 34 minutes
Additional Time 2 hours
Total Time 3 hours 4 minutes

Ingredients

Blackberry Mousse

  • 3/4 cup good quality white chocolate chips (135g)
  • 1 cup heavy cream or heavy whipping cream, cold - divided (240g)
  • 1/3 cup seedless blackberry jam (75g)
  • Regal purple gel food coloring - optional
  • 1/3 cup powdered sugar (42g)
  • 1 tsp vanilla extract (4g)
  • 1/8 tsp fine salt

Blackberry Swirled Cake Recipe

  • 1 cup or 2 sticks unsalted butter, room temperature (226g)
  • 2 1/2 cups granulated sugar (500g)
  • 1 cup pasteurized egg whites from a carton or about 7 egg whites, room temperature (235g)
  • 3 cups cake flour (360g)
  • 2 1/2 tsp baking powder (10g)
  • 1 tsp fine salt (6g)
  • 1 1/2 cups full-fat sour cream, room temperature (380g)
  • 1/4 cup vegetable oil (56g)
  • 1 tsp vanilla extract (4g)
  • 1/2 cup blackberry jam (112g)

Blackberry Buttercream Frosting

Additional Filling and Decoration

Recommended Tools and Equipment

Instructions

Blackberry Mousse Cake Filling

  1. Make the blackberry mousse first so it has time to chill. Or better yet, make this mousse in advance! It can be made 1-2 days ahead of time.
  2. Add 3/4 cup white chocolate chips and 1/4 cup heavy cream in a medium-sized, heat-proof bowl. Heat for 45-60 seconds in the microwave, then let the mixture sit for a minute. Stir until combined with a rubber spatula. The white chocolate should be completely melted, and the mixture should be smooth. If you don't have a microwave, you can also use a double boiler.
  3. Stir 1/3 cup of blackberry jam into the white chocolate mixture. If desired, add a small squirt of purple gel food coloring to give this mousse a more vibrant purple color. Mix thoroughly until the mixture is smooth and there are no clumps of jam. Set aside.
  4. Add 3/4 cup of heavy cream, 1/3 cup powdered sugar, 1 tsp vanilla extract, and 1/8 tsp fine salt into a large bowl or the bowl of a stand mixer fit with a whisk attachment.
  5. Mix on a medium-high speed until the whipped cream starts to gather in the whisk attachment and you can see texture around the edge of the bowl. The whipped cream should be thick and able to keep its shape. This usually takes about a minute or two in my stand mixer.
  6. Gently fold half of the whipped cream into the blackberry white chocolate mixture using a rubber spatula. Use the spatula to swoop around the sides of the bowl and pull through the center. Fold in the remaining whipped cream. Be careful not to over-mix the mousse, or it will become deflated and lose its structure.
  7. Cover the mousse with plastic wrap and chill in the refrigerator for at least 2 hours. Make sure you keep the mousse chilled until right before you fill the cake because it can lose its shape if it gets warm.

Blackberry Swirled Cake Layers

  1. Next, make the blackberry swirled cake layers! Preheat the oven to 350°F / 175°C. Line and grease three, 8-inch cake pans with parchment paper and nonstick baking spray or homemade cake release. If you don't have 3 cake pans, the batter can sit at room temperature for a few hours. Bake as many layers at a time as you can at a time.
  2. Add 1 cup of unsalted butter and 2 1/2 cups of granulated sugar into the bowl of a stand mixer. Mix together on a high speed with a whisk attachment for 3 minutes. Scrape down the sides of the bowl as needed with a rubber spatula. The mixture should become lighter in color as air is whipped into it.
  3. Add in 1 cup of room temperature egg whites and mix at a medium speed until they're incorporated.
  4. Whisk 3 cups of cake flour, 2 1/2 tsp baking powder, and 1 tsp salt together in a separate bowl.
  5. Add half of the dry ingredients into the butter/egg mixture and mix on a low speed until combined.
  6. Add in 1 1/2 cups sour cream, 1/4 cup oil, and 1 tsp vanilla extract and mix at a low speed until combined. Scrape the sides and bottom of the bowl as needed.
  7. Mix in the remaining dry ingredients on a low speed.
  8. Pour half of the batter evenly between the prepared cake pans. I added about 275g of batter per pan.
  9. Drizzle 1/2 cup of blackberry jam over the cake batter. I put my jam in a piping bag to make it easier to drizzle, but you can also use a spoon. Use a small offset spatula or butter knife to swirl the blackberry jam into the cake batter.
  10. Top with the remaining batter, adding another 275g of batter to each pan. Smooth the batter with a spatula or small offset spatula so that it's even across the pan. Layering the jam in the middle of these cake layers will give them a beautiful swirl when you cut into the cake. It also will prevent the jam swirl from being cut off when you level the cake layers later!
  11. Bake for 32-35 minutes, or until a toothpick comes out with a few moist crumbs. Rotate the pans halfway through to help them bake evenly. Note that this recipe doesn't brown as much as my vanilla layer cake recipe, so be sure to test the layers with a toothpick rather than rely on visual browning cues!
  12. Let the pans cool for 10 minutes, then run an offset spatula around the perimeter of the pan to separate the cake from the pan.
  13. Place the cake layers into the freezer for 45 minutes to accelerate the cooling process. Once the layers are fully cooled, carefully flip the pans, and remove the layers from the pans.
  14. Use a serrated knife to level the top of each cake layer. If you make these in advance, wrap and freeze them at this point.

Blackberry Buttercream Frosting

  1. While the cake layers bake and cool, make the blackberry buttercream frosting.
  2. Beat 2 cups butter on a low speed for 30 seconds with a paddle or whisk attachment until smooth.
  3. Add in 1 Tbsp vanilla extract and 1/2 tsp salt and beat on a low speed.
  4. Gradually mix in 6 cups of powdered sugar and 1 Tbsp of lemon juice on a low speed. Continue to mix until the ingredients are fully incorporated.
  5. Scoop 1/3 cup of white frosting into a small piping bag fit with a small French piping tip and seal the top of the bag with a clip or rubber band. Set aside.
  6. Mix 1/2 cup of blackberry into the remaining frosting on a low speed until combined and the desired consistency is reached. If the frosting seems too thick, add in additional cream (1 teaspoon at a time). If the frosting is too thin, add in more powdered sugar (quarter of a cup at a time).
  7. Place 1 cup of the frosting in a separate bowl and color it a pink-purple color by adding in a squirt of pink gel food coloring. Place this frosting in a small piping bag fit with an open star piping tip (like a Wilton 1M) and set aside.
  8. Add a squirt of purple gel food coloring into the remaining frosting and stir until it's evenly colored. Place the purple frosting in a large piping bag. Seal the top of the bag with a rubber band or clip and cut an opening that's about 3/4-inch wide at the base of the bag. Set aside.

Assembling This Blackberry Mousse Cake

  1. Stack and frost the cake layers on a greaseproof cake board using a dab of frosting to help stick the first cake layer to the board.
  2. Pipe a double ring of purple blackberry buttercream around the perimeter of the cake layer. Spread 1/4 cup of blackberry jam inside the frosting ring, then top it with an even layer of blackberry mousse. Use a little less than 1/2 of the mousse between each layer (you will end up having a tiny bit leftover). Gently press blackberries into the mousse.
  3. Chill the cake in the freezer for about 10 minutes, then repeat with the next cake layer. This helps lock the filling in place and prevents the layers from sliding around as you frost the cake. Once all the cake layers are stacked, spread a thin coat of frosting around the cake to fully cover the cake layers. If your layers are sliding around, insert a chopstick or wooden dowel into the center of the cake to make it more stable.
  4. Smooth using a bench scraper, then chill the cake in the fridge (30 minutes) or freezer (10 minutes) until the frosting is firm to the touch.
  5. Add a second, thicker layer of purple blackberry buttercream to the cake and smooth using a bench scraper.
  6. Color any remaining purple buttercream a deeper shade of purple by adding a squirt of purple gel food coloring. Place this frosting in a small piping bag fit with a small French piping tip and seal the top of the bag with a clip or rubber band.
  7. Pipe swirls of the different colors of buttercream in a curved line around the side of the cake and up on top of the cake like in the pictures above. Start with the pink buttercream and pipe large buttercream rosettes, then gently press some fresh blackberries into place. Fill in the gaps with swirls and dollops of the other colors of buttercream, then enjoy!

Notes

Tips for Making the Best Blackberry Mousse Cake

  • When making the blackberry mousse, chill your mixing bowl and whisk attachment in the freezer. It makes it easier and quicker to whip up the whipped cream for the mousse.
  • Properly measure your flour (spoon into the cup measure, then level). Or better yet, use a kitchen scale to measure your dry ingredients.
  • Mix your cake batter just until the ingredients are incorporated after adding in the flour. This ensures your cake layers are tender and fluffy.
  • Use a scale to weigh your cake pans as you fill them. This will make your cake layers bake to the same height and bake more evenly.
  • Bang your cake pans on the counter before putting them in the oven. This brings any air bubbles that are trapped in the batter to the surface.
  • Level your room temperature or thawed cake layers with a serrated knife to make them easier to stack.
  • Chill the leveled cake layers in the freezer for about 20 minutes before assembling the cake. It makes it so much easier to frost them!

Making This Blackberry Mousse Cake in Advance and Storage Tips

  • Make your cake layers in advance and freeze them. It breaks the process up and makes it more approachable.
  • Make your frosting ahead of time too or save any leftover frosting! It can be stored in an airtight container in the fridge for up to a month, or in the freezer for up to 3 months. Be sure to give it a good stir once it thaws to get the consistency nice and smooth again.
  • The blackberry mousse filling in this cake can be made up to two days in advance if stored in an airtight container in the fridge.
  • A frosted cake can last in the fridge for up to 2 days.

Nutrition Information

Yield

24

Serving Size

1

Amount Per Serving Calories 686Total Fat 35gSaturated Fat 20gTrans Fat 0gUnsaturated Fat 13gCholesterol 87mgSodium 280mgCarbohydrates 90gFiber 2gSugar 69gProtein 5g

corina

Sunday 18th of September 2022

I love that your recipe uses carton egg whites! I can't wait to try the hybrid buttercream recipe. Would one batch of the hybrid recipe work for this cake since you are only using it for the dam and the outside of the cake? I noted that you don't recommend doubling the recipe so I hope one batch is enough.

Chelsweets

Tuesday 20th of September 2022

Hi Corina,

One batch of my hybrid frosting should work for this recipe! You could 1.5x the frosting recipe if you are worried about it, but it just will take quite a long time for the egg whites to whip up!!

I do think that frosting recipe is thick enough to keep in the blackberry mousse and jam in the cake. But do a thick, double ring of frosting just to be safe :) Hope that helps, happy baking!!

Jae

Thursday 15th of September 2022

Can I have the link for the cake recipe please? I'd love to try this entire recipe

Chelsweets

Tuesday 20th of September 2022

Hi Jae,

For sure! The recipe with the entire recipe (including the cake) is located right above the comments section in this post :) Happy baking!

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