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Brownie Oreo Cake

It’s my brother-in-law’s birthday and this year I wanted to recreate the epic 5-layer brownie Oreo cake I made him in 2016.

His lucky number is 5, and he jokingly said he’d like a five-layer cake.

Little did he know, his comment would result in this ginormous cake!

image of a brownie oreo cake that's been frosted with oreo buttercream and cut into to show it's alternating layers or oreo cake and brownie

It has alternating layers of tender Oreo cake and brownies and is frosted with homemade Oreo buttercream.

While this cake does have a few different components, it’s totally worth the effort!! I recommend making this cake in stages so that you can enjoy the process.

How to Make This Brownie Oreo Cake

To make sure this 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 Oreo Cake Layers

Make the Oreo cake layers first. Once the batter is made, pour it evenly between the prepared, 8-inch cake pans.

I like to use a scale to make sure each pan has the same amount of batter and will bake up to be the same height.

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

Bake for 34-36 minutes or until a toothpick comes out with a few moist crumbs.

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.

Once the layers are fully cooled, carefully flip the pans and remove the layers from the pans. Use a serrated knife to level the tops of the cooled cake layers.

image of an oreo cake layer that's been leveled with a serrated knife

If you make these in advance, wrap and freeze them at this point. When you’re ready to use them, let them thaw for about 20 minutes before making your cake.

The cake layers should still be slightly cold to the touch, which will make it easier to assemble your cake.

Step 2: Make the Brownie Layers

Next, make the brownies! It’s a big batch, but we need a lot of brownies to fill the cake and decorate it.

Line and grease 2 round, 8-inch cake pans and 1 square, 8-inch cake pan.

Divide the batter evenly between the prepared pans.

image of brownie batter being mixed together

Bake in a preheated oven for 43-53 minutes. The circular pans should take about 5 minutes longer to bake than the square pan.

Remove from the oven and let the pans cool on wire rack, then set aside.

image of oreo cake layers and brownie layers that are cooling on a wire rack

Step 3: Make the Oreo Buttercream

While the cake layers and brownies bake and cool, make the Oreo buttercream frosting.

Mix the frosting on the lowest speed with a paddle attachment once it’s made to push out any excess air, then add in the crushed Oreos.

image of oreo buttercream that's been mixed in a clear glass kitchenaid bowl

I also like to stir the frosting by hand with a rubber spatula once it’s fully made. This makes the frosting nice and smooth and easier to smooth onto your cake.

If the frosting seems too thick, add in additional cream (1 Tbsp at a time). If the frosting is too thin, add in more powdered sugar (quarter of a cup at a time). Cover with plastic wrap and set aside.

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

Step 4: Assembling This Oreo Brownie Cake

Stack and frost the alternating Oreo and brownie layers on a greaseproof cake board using a dab of frosting to help stick the first cake layer to the board.

Add an even layer of Oreo buttercream between each cake layer and brownie layer.

image of oreo cake layers and brownie cake layers being stacked with oreo buttercream frosting

Spread a thin coat of frosting around the the cake to fully cover the cake layers.

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.

image of oreo frosting being smoothed onto an oreo brownie cake

Step 5: Spread on a Thick, Second Layer of Frosting & Decorate

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

If you want to add a drip around the cake, use my chocolate ganache drip recipe.

image of a chocolate ganache drip being added to an oreo brownie cake

Cut up the remaining square pan of brownies into small, 1-inch squares.

Use them to decorate the top of the cake with buttercream swirls and Oreos, then enjoy! Use a sharp, warm knife to cut clean slices.

image of a brownie square being added to the top of a brownie oreo cake

Brownie Oreo Cake Recipe Variations

This recipe can also be used to make a sheet cake! One batch will make 2, 9-inch x 13-inch cake layers that are about 1 inch tall.

Use the brownie batter to bake one 9-inch x 13-inch sheet pan of brownies and place it in between the cake layers.

Tips for Making the Best Brownie Oreo Layer Cake

  • Ingredients at room temperature mix together better! Set out any cold ingredients ahead of time.
  • 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. 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 it 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 brownie oreo cake that's been frosted with oreo buttercream and cut into to show it's alternating layers or oreo cake and brownie

Making This Brownie Oreo Cake in Advance & Storage Tips

Make your cake layers and brownies 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.

A frosted cake can last in the fridge for up to a week, or in the freezer for up to a month. The buttercream locks in all the moisture, keeping the cake fresh and delicious!

If you cut into the cake and have leftovers, use any remaining frosting to cover the cut section to keep it moist and store in the fridge for up to a week.

image of an oreo brownie cake that's been decorated with a chocolate drip and brownie bites

Let Me Know What You Think

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

Don’t forget to tag me @chelsweets and use #chelsweets on social media so I can see your amazing creations!

Other Recipes You Might Like:

Yield: 48 slices

Brownie Oreo Cake

This brownie Oreo cake is the most epic 5-layer cake! It's made with alternating layers of oreo cake and brownies and is frosted with homemade Oreo buttercream!

Prep Time 30 minutes
Cook Time 35 minutes
Additional Time 1 hour
Total Time 1 hour 50 minutes

Ingredients

Oreo Cake Layers

  • 3 cup all-purpose flour (375g)
  • 3 cups granulated sugar (600g)
  • 2 1/2 tsp baking powder (10g)
  • 1 tsp fine salt (6g)
  • 1 cup or 2 sticks unsalted butter, room temperature (226g)
  • 1 cup pasteurized egg whites from a carton or about 7 egg whites, room temperature (235g)
  • 1 1/2 cups buttermilk, room temperature (345g)
  • 2 Tbsp vegetable oil (28g)
  • 2 tsp vanilla extract (8g)
  • 1 cup chopped Oreos - about 9 Oreos (75g)

Brownie Layers

  • 4 1/2 cups granulated sugar (900g)
  • 2 1/4 cups all-purpose flour (280g)
  • 2 cups unsweetened baking cocoa (160g)
  • 1 1/2 cups powdered sugar (190g)
  • 1 1/2 cups milk or dark chocolate chips (255g)
  • 2 tsp fine salt (12g)
  • 6 large eggs, room temperature (336g)
  • 1 1/2 cups vegetable or canola oil (340g)
  • 1/3 cup water (80g)
  • 1 Tbsp vanilla extract (12g)

Oreo Buttercream Frosting

  • 3 cups unsalted butter, room temperature (678g)
  • 1 Tbsp vanilla extract (12g)
  • 1 tsp fine salt (6g)
  • 11 cups powdered sugar (1375g)
  • 1/2 cup heavy cream or whipping cream, room temperature (120g)
  • 1 cup finely crushed Oreo crumbs - about 12 Oreos (100g)

Recommended Tools & Equipment

Instructions

Oreo Cake Layers:

  1. Preheat oven to 350°F/175°C. Line three, 8-inch pans with parchment rounds and grease with non-stick cooking spray.
  2. Whisk together 3 cups all purpose flour, 3 cups sugar, 2 1/2 tsp baking powder and 1 tsp salt in the bowl of a stand mixer or in a large bowl until combined.
  3. Mix in 1 cup of room temperature, unsalted butter slowly into the dry ingredients on a low speed with either a paddle attachment or a hand mixer. Continue to mix until no large chunks of butter remain and the mixture looks like moist sand.
  4. Pour in 1 cup of egg whites and mix on low until just incorporated. Mix in 1 1/2 cups buttermilk in two installments, on a low speed.
  5. Add in 2 Tbsp of vegetable oil and 2 tsp of vanilla extract. Mix on a low speed until combined.
  6. Scrape down the sides of the bowl with a rubber spatula, then beat on a medium speed for about 30 seconds to make sure everything is properly mixed together.
  7. Gently fold 1 cup of chopped Oreos into the batter and pour it evenly between the prepared cake pans. I like to use a kitchen scale to make sure each pan has the same amount of batter and will bake up to be the same height.
  8. Bake for 34-36 minutes or until a toothpick comes out with a few moist crumbs. 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.
  9. Place cake layers into the freezer for 30 minutes to accelerate the cooling process. Once the layers are fully cooled, carefully flip the pans and remove the layers from the pans.
  10. Use a serrated knife to level the tops of the cooled cake layers. If you're making these in advance, wrap and freeze them at this point.
  11. If you make these cake layers in advance and freeze them, let them thaw for about 20 minutes before making your cake. The cake layers should still be slightly cold to the touch, which will make it easier to assemble your cake.

Brownie Layers:

  1. Keep the oven on and make the brownie layers next! This is a triple batch of brownies, so make sure you get out your biggest bowls.
  2. Line and grease 2 round, 8-inch cake pans and 1 square, 8-inch cake pan.
  3. Whisk together 4 1/2 cups sugar, 2 1/4 cups flour, 2 cups baking cocoa, 1 1/2 cups powdered sugar, 1 1/2 cups chocolate chips, and 2 tsp salt in a large bowl. Set aside.
  4. In a separate large bowl whisk together 6 large eggs, 1 1/2 cups vegetable oil. 1/3 cup water, and 1 Tbsp vanilla extract.
  5. Add the dry ingredients into the wet ingredients and stir until combined.
  6. Divide the brownie batter evenly between the prepared pans (about 830g per pan).
  7. Bake in a preheated 350°F/175°C oven for 43-53 minutes. The circular pans should take about 5 minutes longer to bake than the square pan.
  8. Remove from the oven and let the pans cool on wire rack. Run an offset spatula around the perimeter of the pan to separate the brownies from the pan while the brownies are still warm.

Oreo Buttercream Frosting:

  1. While the cake layers and brownies bake and cool, make the Oreo buttercream frosting.
  2. Beat 3 cups of unsalted butter on a medium speed for 30 seconds with a paddle attachment until smooth.
  3. Mix in 1 Tbsp of vanilla extract and 1 tsp salt on a low speed.
  4. Slowly mix in 11 cups of powdered sugar on a low speed. Add 1/2 cup of heavy cream halfway through to make the frosting easier to mix.
  5. Continue to mix on low speed for a few minutes, until the desired consistency is reached. 
  6. If the frosting seems too thick, add in additional cream (1 Tbsp at a time). If the frosting is too thin, add in more powdered sugar (quarter of a cup at a time).
  7. Fold in 1 cup of finely crushed Oreos until they're evenly distributed throughout the frosting. Cover with plastic wrap and set aside.

Assembling This Brownie Oreo Cake:

  1. Stack and frost the alternating Oreo cake and brownie layers on a greaseproof cake board using a dab of frosting to help stick the first cake layer to the board.
  2. Add an even layer of Oreo buttercream between each cake layer and brownie layer.
  3. Spread a thin coat of frosting around the cake to fully cover the cake layers. 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.
  4. Add a second, thicker layer of Oreo frosting to the cake, and smooth using a bench scraper.
  5. If you want to add a drip around the cake, use my chocolate ganache drip recipe.
  6. Cut up the remaining square pan of brownies into small, 1-inch squares. Use them to decorate the top of the cake with buttercream swirls and Oreos, then enjoy! Use a sharp, warm knife to cut nice clean slices.

Notes

Yield:

One batch of cake batter makes about 1900 grams, so when I'm making a cake with three layers I add about 630 grams of batter into each pan.

One batch of brownie batter makes about 2500 grams of batter, so you can add about 830 grams per pan.

Brownie Oreo Cake Recipe Variations

This recipe can also be used to make a sheet cake! One batch will make 2, 9-inch x 13-inch cake layers that are about 1-inch tall. Use the brownie batter to bake one 9-inch x 13-inch sheet of brownies and place it in between the cake layers.

Tips for Making the Best Brownie Oreo Layer Cake

  • Ingredients at room temp mix together better! Set out any cold ingredients ahead of time.
  • 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. 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 it 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!

Making This Brownie Oreo Cake in Advance & 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.

A frosted cake can last in the fridge for up to a week, or in the freezer for up to a month. The buttercream locks in all the moisture, keeping the cake fresh and delicious!

If you cut into the cake and have leftovers, use any remaining frosting to cover the cut section to keep it moist and store in the fridge for up to a week.

Nutrition Information

Yield

48

Serving Size

1

Amount Per Serving Calories 530Total Fat 21gSaturated Fat 12gTrans Fat 0gUnsaturated Fat 8gCholesterol 69mgSodium 319mgCarbohydrates 82gFiber 1gSugar 67gProtein 5g

For a walk down memory lane, below are some picture from when I first made this cake in 2016.

image1

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