Hot Cocoa Fudge Cake
This hot cocoa fudge cake is made with moist chocolate cake layers brushed with hot cocoa simple syrup, rich milk chocolate ganache, and airy homemade marshmallow fluff. It’s basically a mug of hot chocolate in cake form!
This Recipe at a Glance
- Yield: One 3-layer, 8-inch cake (about 24 servings)
- Cake: Moist chocolate layers brushed with hot cocoa simple syrup
- Filling: Thick milk chocolate ganache and homemade marshmallow fluff
- Frosting: Light, whipped chocolate ganache
How to Make This Hot Cocoa Fudge Cake
This cake has several components, but making them in stages makes it feel a lot more manageable. I recommend making the ganache first so that it has time to thicken, followed by the cake layers. Then make the hot cocoa simple syrup while the cake layers cool and whip up the marshmallow fluff last (it’s fluffiest when it’s fresh).
Step 1: Make the Milk Chocolate Ganache
Start by heating the heavy cream until it just begins to steam and bubble. Add the milk chocolate chips, making sure they’re covered with cream, and let the mixture sit for a minute before gently stirring until smooth.
Mix in the room-temperature butter, optional corn syrup, and salt. Pour the ganache into a wide, shallow container, cover, and let it cool until thick and spreadable. You can also make it in advance. Don’t assemble the cake while the ganache is warm or runny—the filling needs to be thick enough to support the cake layers.
This recipe makes enough ganache to fill the cake and whip the remaining portion into frosting. If you prefer a less sweet chocolate flavor, the recipe card also includes an adjusted ratio for dark chocolate ganache.
Step 2: Bake the Chocolate Cake Layers
Preheat the oven to 350°F/175°C. Line three 8-inch cake pans with parchment rounds and grease the sides. In a large bowl, whisk together the flour, sugar, unsweetened cocoa powder, baking powder, baking soda, and salt.
In a separate bowl, whisk together the warm water, room-temperature buttermilk, vegetable or canola oil, eggs, and vanilla.
Add the dry ingredients to the wet ingredients and whisk just until the batter is smooth.
Divide the batter evenly between the prepared pans (about 475g or 2 cups of batter per pan if you’re making 3 layers) and bake for 24–26 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Let the pans cool for 10 minutes, then loosen the edges with a small offset spatula.
I like to place the pans in the freezer for about 30 minutes to speed up cooling and help keep the cake layers moist. Once they’re completely cool, carefully remove them from the pans. Level with a serrated knife if needed.
Step 3: Make the Hot Cocoa Simple Syrup
Combine the water and granulated sugar in a small saucepan. Cook over medium heat, stirring until the mixture begins to boil and the sugar has completely dissolved, about 3 minutes.
Remove from heat, stir in the hot cocoa mix until combined, and let it cool to room temperature.
If you bake and freeze the cake layers in advance, freeze them without the syrup. Brush the cooled simple syrup onto the cake layers as you stack them.
Step 4: Make the Homemade Marshmallow Fluff
Once the cake layers, ganache, and hot cocoa simple syrup are ready, make the marshmallow fluff. Combine the water, granulated sugar, and corn syrup in a saucepan and cook over medium-high heat with a candy thermometer. Once it begins heating, avoid stirring so the sugar doesn’t crystallize.
While the syrup heats, wipe your stand mixer bowl and whisk with a little lemon juice or vinegar to remove any grease. Add the egg whites and cream of tartar. When the syrup reaches 225°F/107°C, begin whipping the whites until soft peaks form.
At 240°F/116°C, carefully pour the hot syrup into the egg whites in a thin stream while the mixer runs on medium speed. Aim between the side of the bowl and the whisk.
Increase the speed and whip until the fluff is thick, glossy, and fluffy. Add the vanilla and continue whipping until it cools to room temperature.
I recommend making the marshmallow fluff right before assembling the cake. It has the best consistency when it’s fresh and can become harder to spread after sitting.
How to Assemble This Hot Cocoa Fudge Cake
Place the first cake layer on a greaseproof cake board or large, flat plate, using a dab of ganache to hold it in place. Brush about a third of the cooled hot cocoa simple syrup over the top of the cake layer and let it absorb before adding the filling.
Spread about 1 1/4 cups (325g) of ganache over the layer. Pipe a sturdy ring of ganache around the edge, then spoon roughly 1 1/2 cups of marshmallow fluff inside the ring.
Add the second cake layer, brush it with the cooled hot cocoa simple syrup, and add another layer of ganache and marshmallow fluff, then place the final cake layer upside down on top. Brush the remaining simple syrup over the top layer.
Chill the stacked cake until the filling is firm, about 15 minutes in the freezer or 30 minutes in the fridge. Whip the remaining room-temperature ganache with a mixer on high for 1–2 minutes, just until it lightens in color and increases in volume.
Cover the chilled cake with the whipped ganache. Use an offset spatula or the back of a spoon to swirl the remaining marshmallow fluff into the whipped ganache for a marbled finish, then enjoy!
Substitutions and Swaps
- All-purpose flour: A good 1:1 gluten-free baking blend works great in place of the AP flour if you need gluten-free cake layers.
- Cocoa powder vs Hot Cocoa Mix: Use unsweetened baking cocoa for the cake layers, and sweetened hot cocoa mix for the simple syrup. If you don’t have hot cocoa mix, you can use baking cocoa powder to make the simple syrup.
- Buttermilk and warm water: The buttermilk adds tenderness and moisture, and the warm water helps bring out the cocoa flavor.
- Neutral oil: Vegetable, canola, or sunflower oil all work well.
- Milk chocolate: If you prefer dark chocolate, follow the chocolate-to-cream ratio for dark chocolate ganache listed in the recipe card rather than making a 1:1 swap.
- Light corn syrup: This is optional in the ganache, but don’t omit it from the homemade marshmallow fluff.
Troubleshooting
Why Is My Ganache Too Thin?
Milk chocolate ganache needs time to cool to room temperature before it thickens. If it’s still loose, let it cool longer or refrigerate it briefly, stirring as needed.
Why Won’t My Marshmallow Fluff Whip Up?
Make sure the bowl and whisk are completely free of grease, the egg whites reach soft peaks before the syrup is added, and the syrup reaches 240°F/116°C. Pour the syrup slowly and keep whipping until the mixture is thick and glossy. A candy thermometer makes this step much more reliable.
How Do I Keep the Marshmallow Filling From Leaking Out?
The key is to use a thick ring of ganache around each layer, keep the marshmallow fluff inside that ring, and avoid overfilling.
Making This Hot Cocoa Fudge Cake in Different Sizes
This recipe makes three 8-inch cake layers. If you want to make a different-sized cake, use my cake batter calculator to figure out how much batter you’ll need.
Baking times will change with the size and depth of your pans, so look for a set center and a toothpick with a few moist crumbs.
Make-Ahead and Storage Tips
Cake layers: Bake the layers in advance, let them cool completely, and wrap them tightly before freezing. Wait to add the hot cocoa simple syrup until you assemble the cake. Let the cake layers thaw slightly until they’re cool but workable, then brush them with the cooled simple syrup right before stacking and filling.
Ganache: The ganache can be made ahead and chilled in an airtight container. When you’re ready to use it, set it out at room temperature for a few hours to let it gradually warm. When it’s ready, it should have a thick, spreadable consistency.
Marshmallow fluff: For the best texture, make it the day you assemble the cake, after the other components are ready. I don’t recommend freezing the homemade fluff separately.
Assembled cake: Store the finished cake covered in the fridge. Because the filling contains homemade marshmallow fluff, it’s best enjoyed within a few days because the fluff can gradually soften or change texture.
Frequently Asked Questions
Can I Use Store-Bought Marshmallow Fluff?
You can, but store-bought fluff can be harder to spread and soften between the layers, so be sure not to overfill it and chill the cake well.
Do I Need to Use the Hot Cocoa Simple Syrup?
The hot cocoa simple syrup adds extra hot chocolate flavor and moisture, but the cake layers are moist on their own. You can omit it if you prefer or just brush on a tiny bit.
Can I Make the Cake Layers Ahead of Time?
Absolutely! I actually recommend baking and freezing the cake layers ahead of time to make assembly easier. Freeze them without simple syrup, then brush the cooled hot cocoa simple syrup onto the layers just before you stack the cake.
Can I Use Dark Chocolate Instead of Milk Chocolate?
Yes! Use the dark chocolate variation in the recipe card. Dark chocolate requires a different cream ratio, so don’t swap it cup for cup with milk chocolate.
Can I Make the Marshmallow Fluff With a Hand Mixer?
A hand mixer can work, but whipping the hot sugar syrup into egg whites is much easier with a stand mixer because it leaves your hands free to pour carefully. Make sure your bowl is heatproof, and the mixture reaches thick, glossy peaks.
Tips for Making the Best Hot Cocoa Fudge Cake
- Measure your flour accurately with a kitchen scale or spoon and level it into the measuring cup.
- Use room-temperature ingredients where the recipe calls for them so the ingredients combine properly.
- Allow the ganache to become thick and spreadable before using it as filling.
- Make the marshmallow fluff shortly before assembling the cake.
- Chill the cake between filling and frosting to keep the layers stable.
Let Me Know What You Think!
If you try this hot cocoa fudge cake recipe, I’d love to hear what you think! Please leave a comment and rating below.
Hot Cocoa Fudge Cake
Equipment
- Scale (optional)
Ingredients
Milk Chocolate Ganache
- 1 1/2 cups heavy whipping cream 360g
- 5 1/2 cups milk chocolate chips 975g
- 3/4 cup (1 1/2 sticks) unsalted butter, room temperature 170g
- 6 Tbsp light corn syrup – optional 120g
- 3/4 tsp fine salt 4g
Marshmallow Fluff
- 1/3 cup water 80g
- 1/2 cup granulated sugar 100g
- 1/2 cup light corn syrup 160g
- 2 large egg whites, room temperature 60g
- 1/3 tsp cream of tartar
- 2 tsp vanilla extract or vanilla bean paste 10g
Chocolate Cake Layers
- 2 cups all-purpose flour 260g
- 2 cups granulated sugar 400g
- 3/4 cup unsweetened cocoa powder, sifted 75g
- 2 tsp baking powder 8g
- 1 1/2 tsp baking soda 9g
- 1 tsp fine salt 6g
- 1 cup water, warm 240g
- 1 cup buttermilk, room temperature 240g
- 1/2 cup vegetable or canola oil 110g
- 2 large eggs, room temperature 112g
- 1 tsp vanilla extract or vanilla bean paste 4g
Hot Cocoa Simple Syrup
- 1/2 cup water 120g
- 1/2 cup granulated sugar 100g
- 2 Tbsp sweetened hot cocoa mix
Instructions
Milk Chocolate Ganache (for the filling & frosting)
- Heat 1 1/2 cups of heavy cream in a large, heatproof bowl in the microwave in 30-second intervals, stirring as needed, until it just begins to bubble and steam. If you don’t have a microwave, heat the cream in a small saucepan over medium heat until it just begins to steam and bubble.
- Gently pour 5 1/2 cups (975g) of milk chocolate chips into the hot heavy cream. Make sure the chips are fully covered with cream. Let the mixture sit for 1 minute. If you prefer dark (60–65% cocoa) chocolate, use 4 cups (720g) of dark chocolate chips and 3 cups of heavy cream instead.
- Stir slowly until the cream and chocolate combine and the mixture is smooth. If any bits of chocolate aren’t fully melted, microwave at half power in 10- to 15-second intervals, stirring well between intervals, until smooth.
- Then mix in 3/4 cup (1 1/2 sticks) of room-temperature unsalted butter, 6 Tbsp (3/8 cup) of light corn syrup (optional), and 3/4 tsp of fine salt until combined.
- Pour the mixture into a shallow, wide tray to help it cool faster, then cover it with plastic wrap to prevent the ganache from forming a skin. Set aside to let it cool to room temperature.
Marshmallow Fluff
- Make the marshmallow fluff shortly before assembling the cake, after the cake layers, simple syrup, and ganache are ready. Combine 1/3 cup (80g) water, 1/2 cup (100g) granulated sugar, and 1/2 cup (160g) light corn syrup in a medium saucepan. Stir to combine, then place a candy thermometer in the pan and heat over medium-high. Avoid stirring once the syrup begins heating to prevent crystallization.
- Wipe the bowl and whisk of a stand mixer with lemon juice or vinegar to remove any grease. Add 2 room-temperature egg whites (about 60g) and 1/3 tsp cream of tartar.
- When the sugar syrup reaches 225°F (107°C), whip the egg whites on medium-high speed until soft peaks form, about 3–4 minutes.
- When the syrup reaches 240°F (116°C), remove it from the heat. With the mixer running on medium speed, carefully pour the hot syrup into the egg whites in a thin, steady stream between the whisk and the side of the bowl.
- Increase the mixer speed to medium-high and whip for 7–8 minutes, until the marshmallow fluff is thick, glossy, and fluffy. Add 2 tsp vanilla extract and continue whipping until the fluff cools to room temperature. Use promptly to fill the cake, since the fluff is easiest to spread when freshly made.
Chocolate Cake Layers
- Preheat oven to 350°F/175°C. Line three 8-inch cake pans with parchment paper rounds and spray the sides with nonstick baking spray. Set aside.
- Sift or whisk together 2 cups flour, 2 cups granulated sugar, 3/4 cup unsweetened cocoa powder, 2 tsp baking powder, 1 1/2 tsp baking soda, and 1 tsp fine salt in a large bowl. Set aside.
- In a separate, large bowl, add 1 cup warm water, 1 cup buttermilk, 1/2 cup oil, 2 eggs, and 1 tsp vanilla and whisk together until fully incorporated.
- Whisk the dry ingredients into the wet ingredients until they're just combined, and the batter is smooth.
- Pour the batter evenly (about 475g or about 2 cups per pan if you're making 3 layers) between the 3 cake pans. Bake for 24-26 minutes, or until a toothpick comes out with a few moist crumbs.
- Let the pans cool for 10 minutes, then run a small offset spatula around the perimeter of the pan to separate the cake from the pan.
- Place the cake pans into the freezer for 30 minutes to accelerate the cooling process. This helps lock in the steam and makes the layers extra moist. If you don't have room in the freezer, place the cake pans on a wire rack and let them cool fully before removing them.
- Once the layers are fully cooled, carefully flip the pans and remove the layers. These cake layers bake up pretty flat, so leveling them is optional, but I like to level them with a serrated knife to make the cake easier to fill and frost.
- If you make these cake layers in advance, let them thaw for about 15 minutes before making the cake. The cake layers should still be slightly cold to the touch, which will make it easier to assemble the cake. Do not add the simple syrup before freezing the layers; brush on the cooled simple syrup right before assembling the cake.
Hot Cocoa Simple Syrup
- Pour 1/2 cup of water and 1/2 cup of granulated sugar into a small saucepan. Cook over medium heat, and stir continuously until the mixture just starts to boil. It usually takes about 3 minutes for my simple syrup to reach a boil. At this point, the sugar should have completely dissolved, and the mixture should look clear.
- Remove from the heat and stir in 2 Tbsp of hot cocoa mix until fully combined. Pour into a separate container and set aside to cool to room temperature. Brush this cooled simple syrup onto the cake layers just before adding the ganache and marshmallow fluff. If making the layers ahead, do not soak them before freezing.
Hot Cocoa Fudge Cake Assembly
- Place the first cake layer on a greaseproof cake board or large flat plate, using a small dab of chocolate ganache to keep it in place. Brush the layer with about a third of the cooled hot cocoa simple syrup.
- Place about 1 cup of room-temperature ganache in a piping bag and seal the top with a rubber band. Cut a 3/4-inch opening at the base of the bag.
- Spread about 1 1/4 cups (325g) of room-temperature chocolate ganache on the first cake layer, then pipe a ring of ganache around the edge of the cake and fill it with about 1 1/2 cups (about 135g) of marshmallow fluff.
- Add the second cake layer and brush it with simple syrup, then add the chocolate ganache and marshmallow fluff to the second cake layer. Place the final cake layer upside down on top to make it easier to frost and minimize crumbing. Brush the top with the remaining simple syrup. Then chill the cake for about 15 minutes in the freezer or 30 minutes in the fridge, or until the filling is firm.
- Whip the remaining room-temperature chocolate ganache with a hand mixer or stand mixer on a high speed for 1-2 minutes, or until the mixture becomes lighter in color and increases in volume.
- Cover the chilled cake with the whipped chocolate ganache. Use a large offset spatula or the back of a spoon to swirl the remaining marshmallow fluff into the whipped ganache for a pretty, marbled finish, then dig in!
Notes
Make Ahead and Freezing Tips
Bake the chocolate cake layers, cool them completely, then wrap tightly and freeze them without the hot cocoa simple syrup. Brush the simple syrup onto the cake layers right before assembling. The chocolate ganache can be made ahead of time and stored in airtight containers in the fridge for up to a week or in the freezer for up to 3 months. Let it sit at room temperature for a few hours to bring it back to the proper consistency before assembling the cake. A cake like this can be stored in the fridge for up to 3 days, but it is best enjoyed on the first or second day. If you do refrigerate the cake, let it sit at room temperature for about an hour before serving so the ganache has time to soften. For the best texture, make the marshmallow fluff the day you plan to assemble the cake rather than preparing it ahead of the cake layers. It can start to lose its structure as it sits.Nutrition
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How do you pulse using the standing mixer? My mixer had only speeds
Hi Serena! I just toggle the switch between the lowest setting and off, which helps keep the speed of the mixer nice and slow 🙂
Hi Chelsea! Since I don’t have a kitchen scale, do you know approx how many cups is equal to 250 grams of heavy cream (for the ganache filling)?
PS Super excited for you in your new full time Chelsweets adventure!
It is 1.08 cups. So pretty much a cup! plus maybe a tablespoon!
Hi Chelsea! I want to do this cake for my son’s party, something different from the usual vanilla cake on a birthday party. Son wants a “wheels on the bus” themed cake, i have to decorate it with a bus.. so i’ll be skipping the drip and the ganache dollops… Do you think it will work well if i cover it with fondant? Or should I just frost it with buttercream? What do you suggest? Thanks!
Ganache works great under fondant, so I think you can make it as is (with buttercream and ganache), and then decorate with fondant! However, if you’re more comfortable working with buttercream under fondant, you can do that too! It all comes down to your preference and what you like working with 🙂 Hope that helps, I’m sure your son’s cake will turn out great!!??
Where did you get your taller bench scraper?
This is actually just a six inch bench scraper! but there is a great taller bench scrapper on amazon, it’s 10 inches tall 🙂 here’s the link: https://amzn.to/2TTxPDv
Thanks! You’re such an inspiration 🙂
I made this for my Nephew’s Birthday and it was a huge hit! He and everyone loved it,
So happy to hear that Sarah!! Thank you for sharing 🙂
I made this cake for my daughter’s birthday and it was absolutely delicious! Trying to make the ganache was a disaster but it was completely my fault. I over read the part about making it in advance. Even though the ganache thickened way too much it still was a hit! The mini marshmallows seemed to get gooey in the middle of the cake which tasted amazing! Thanks for the recipe!
Haha well happy it sounds like in the end it was a big success!! Ganache does firm up quite a bit one it fully cools, that part is normal! 🙂
Hi there, really love your Instagram feed! I was just curious, if I wanted to add more marshmallow fluff to the marshmallow buttercream, would I also have to add more powdered sugar to keep it from being too soft? Thanks in advance!
Thank you Holly! It actually is super sticky, so you’d just need to add a bit more heavy cream if you add additional marshmallow fluff! Hope that helps, I fully support that!!! 😛
Hi Chelsea,
First off, I love your recipes! Second, I plan on making this caking in a couple of weeks but was hoping I could make a smaller 6″ cake. In your video you mention adjusting the recipe to fit your needs but what recommendation do you have for 6″ 3 layer cake? Thank you! Can’t wait to try this 🙂
Thanks Kayley! I actually have a great small batch chocolate cake recipes that works great for 6 inch pans! You can adjust down the amount of filling and frosting you make to match the cake layers.
Here’s the link: https://chelsweets.com/2019/09/09/small-batch-chocolate-cake-recipe-6-inch-cake/
Hope that helps, happy baking!
Do you have a printable version of the Hot Chocolate Cake?
Hi Lisa,
Sadly I haven’t had a chance to covert it over to my recipe card plug-in yet :/ I’m so sorry!!
Hey,
I would like to make this cake but I want only two or three cake layers. What would be the proportions of the ingredients?
Thanks
Hi Lucy,
That can vary a ton based on the size of you cake pans! One batch of this batter can be used to make 3, 8″ cake layers. Hope that helps!!
I’m really wanting to make this cake but I dont know what the equivalent to powdered sugar is here in the uk as I cannot find that anywhere, also is the confectioners powdered sugar the same as normal as I’ve noticed it’s used alot in your recipes so just for future reference lol 🙂 your cakes are absolutely amazing and have defo inspired me to try baking xx
I’m planning on making hot cocoa cupcakes but I only need 12… Any advice on how to cut the recipe down?
Can I use swiss meringue buttercream for this cake
I made this cake today for my birthday. It is absolutely delicious! I only have 9″ cake pans so I ran into some troubleshooting (ran out of buttercream and had to make an extra half batch, etc) that I didn’t think through in advance. Also the ganache set way way too firm, so I had to thin it out with a little more cream and heat in brief increments until it was a spreadable consistency then let it cool before using. In the end it all came together well, looks, and tastes great…I just didn’t account for just how much bigger a 9″ pan really is compared to an 8.” No fault with the recipe, that’s on me. My only real complaint is the marshmallow buttercream didn’t taste at all like marshmallow…in the future I would play with adding more marshmallow fluff.
does the chocolate ganache sit out all night? or does it go in the refrigerator once it’s covered in plastic wrap?
Hi Shima,
I usually store it in the fridge if I make it in advance, but it can sit at room temperature for a day! So it can sit out overnight if you plan to use it the next day. Hope that helps, happy baking!