Elegant, moist and delicious Chocolate Mousse Cake recipe filled with an easy homemade chocolate mousse, and warm chocolate frosting poured on top.
Want more cake recipes? Try my German Chocolate Cake, Berry Cake, or Coconut Cake with Pineapple Filling!
Why I love this easy mousse cake:
- Prep Ahead – The chocolate mousse recipe couldn't be easier to make, and you can prep everything in advance!
- Elegant – Fancy enough to impress any guests, especially a chocolate lover!
- Delicious – The chocolate cake is moist and divine. The chocolate mousse filling is creamy and pairs perfectly with the cake. This will become your new favorite cake!
How to make Chocolate Mousse:
Make the Mousse: Start by mixing the cocoa powder and hot water together until smooth. Melt chocolate chips in the microwave, or using a double boiler. Add the cocoa powder mixture to the melted chocolate and stir until smooth. Allow to cool to room temperature.
Whip the cream and sugar together in a large mixing bowl until very stiff peaks. Add the cooled melted chocolate and gently fold the mixture together to combine. Refrigerate until ready to use.
How to make Chocolate Mousse Cake:
Bake Chocolate Cake: Stir together sugar, flour, cocoa powder, baking powder, baking soda, and salt in a large bowl. Add eggs, milk, oil, and vanilla. Beat on medium speed for 2 minutes. Stir in boiling water then pour into prepared pans. Bake at 350 degrees for 30-35 minutes, or until a toothpick inserted comes out clean. (If you don't want to make the cake from scratch, you can use a box cake mix).
Halve the Cake Rounds: Once the cakes have cooled use a sharp serrated knife to torte them in half, lengthwise, so you have four thin layers of chocolate cake.
Stack Cake with Mousse Filling: Place the first cake layer on your serving tray. Smooth a thin layer of chocolate mousse over it, and top with the next layer of cake. Repeat to assemble a cake with chocolate mousse between each layer. Smooth any extra chocolate mousse you have over the outsides of the entire cake to make a”crumb” coat to seal the cake.
Refrigerate the cake for at least 30 minutes (or up to 1-2 days, covered) while you make the chocolate frosting.
Make Frosting: Combine milk, cocoa, and butter in a medium saucepan. Bring to a boil then remove from heat. Add powdered sugar and mix with electric beaters to get rid of any lumps. Cool for at least 15-20 minutes, stirring occasionally. Be sure to allow the frosting to cool long enough. You want it soft enough to still be “pourable” but you don't want it to be so warm that it melts the mousse into a puddle.
Pro Tip: Lay pieces of parchment paper around, and gently under the edges of the cake to catch the frosting as it drips down. I usually just pour the frosting slowly and catch it as it comes down the sides of the cake, smoothing it along the sides of the cake.
Make Ahead Instructions:
- Chocolate Mousse: Place in an airtight container in the fridge for up to 5 days. Fold it again gently with a spatula before using. But the texture is best the day of.
- Cake Rounds: These can be made in advance and frozen. Once baked, cool them completely and then wrap them in a double layer of plastic wrap. Place in a freezer safe bag and freeze for up to 3 months.
More Desserts to Try:
- Chocolate Peanut Butter Cake
- Meringue Roulade
- Chocolate Milkshake
- S'mores Bars
- Panna Cotta
- Tres Leches Cake
- World's Best Peanut Butter Bars
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Recipe
Chocolate Mousse Cake
Equipment
Ingredients
Chocolate Cake:
- 2 cups granulated sugar
- 1 3/4 cups + 2 Tbsp all-purpose flour
- 3/4 cup unsweetened cocoa powder
- 1 1/2 teaspoons baking powder
- 1 1/2 teaspoons baking soda
- 1 teaspoon salt
- 2 large eggs
- 1 cup buttermilk
- 1/2 cup oil (vegetable or canola oil)
- 2 teaspoons vanilla extract
- 1 cup boiling water , or hot coffee
Chocolate Mousse:
- 1/2 cup hot water
- 4 Tablespoons unsweetened cocoa powder
- 1 1/2 cups semi-sweet chocolate chips
- 2 cups heavy whipping cream
- 2 Tablespoons granulated sugar
Chocolate Frosting:
- 6 Tablespoons milk
- 3 Tablespoons unsweetened cocoa powder
- 1/2 cup butter (one stick)
- 3 3/4 cups powdered sugar
Instructions
Chocolate Cake:
- Heat oven to 350°F. Grease and flour two 8 or 9 inch round baking pans. (I like to line the bottom of mine with wax or parchment paper).
- Stir together sugar, flour, cocoa powder, baking powder, baking soda and salt in large bowl.
- Add eggs, buttermilk, oil and vanilla; beat on medium speed of mixer 2 minutes.
- Stir in boiling water (the batter will be thin). Pour batter into prepared pans.
- Bake for about 30 to 35 minutes or until a toothpick inserted in the center comes out clean.
- Allow cake to cool in the pan for 5 minutes and then remove to wire cooling racks. Cool completely. (You could freeze the cake rounds at this point, if desired.)
Chocolate Mousse:
- Stir the cocoa powder and hot water together. In a double-boiler (or in the microwave) melt the chocolate chips, just until smooth. Add the cocoa mixture to the melted chocolate chips and stir well to combine. Allow to cool to room temperature.
- In a separate large bowl, beat the cream and sugar until very stiff peaks form. Add the chocolate mixture and fold in with a spatula until well combined. Refrigerate until ready to use, up to 5 days.
Chocolate frosting:
- In a medium saucepan, add milk, cocoa, and butter. Bring to a boil. Remove from heat.
- Add powdered sugar and mix with electric beaters to get rid of any lumps. Allow to cool for 15-20 minutes, stirring occasionally.
Assembly:
- Once cakes have cooled, use a sharp serrated knife to torte each cake (cut each cake evenly in half, horizontally, so that you end up with four, thin, 9” cake pieces).
- Place your first cake layer on your cake serving plate. Spread a big spoonful of mousse on top of that cake layer. Repeat with the remaining cake layers, adding a layer of mousse filling between each layer of cake.
- Use remaining mousse filling to spread it evenly around the entire outside and top of the cake. Refrigerate for 30 minutes.
- (I usually make the warm chocolate frosting while the cake is in the fridge.)
- Remove cake from fridge and very slowly pour the cooled chocolate frosting over the top. Use a spatula or knife to gently spread the frosting evenly over the outside of the cake as you pour.
- Refrigerate until ready to serve.
Notes
- Mousse: Place in an airtight container in the fridge for up to 5 days. Fold it again gently with a spatula before using. But the texture is best the day of.
- Cake Rounds: These can be made in advance and frozen. Once baked, cool them completely and then wrap them in a double layer of plastic wrap. Place in a freezer safe bag and freeze for up to 3 months.
Nutrition
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*I first shared this recipe in May 2014. Updated May 2018 and February 2022.
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I’ve made this cake twice; once with the mousse from the recipe and once with just the cake and a white chocolate buttercream. Something this delicious shouldn’t be this easy too. Awesome recipe and my new go-to chocolate cake.
Thanks Michele! So happy you liked it 🙂
This cake was super tasty, and the mousse was particularly delicious BUT the 20 minute prep time, 40 minute cook time, and 1 hr total was just completely unrealistic. I would have needed two other people assisting to make the cake that quickly. I made the mousse first, and it was a complete flop. I then googled how to make whipping cream and made a second batch (do put the bowl and mixers in the freezer, do not add the sugar until after the cream thickens). I then made the cake, which was easy enough, but it has to cook for 35 minutes and then cool for another 30, and then be sliced (very thin layers – I wish I had just made four cakes). Even then, it was still too warm for the mousse, and the mousse melted into it a bit. I then refrigerated the cake again and made the icing, which had to cool 10 minutes per the recipe. This was definitely not enough cooling time, and the cake started falling in once I began pouring the icing over it. I bake from scratch a lot, and this was the most difficult cake I’ve ever made. The flavor was great, but it just wasn’t worth the effort.
Hi Ashley,
Thank you for the feedback. I have updated the time to be more accurate and reflect that fact that there is about 40 minutes of refrigeration/cool time with this recipe! When I make this recipe I like to make the cake the day before so that the whole process goes quicker. You could also make the frosting ahead of time!
As I said before I made the cake but I left the filling in the fridge overnights so it was a bit hard should I have blended it again to soften it. Also how do you pour the frosting without getting the plate all messy don’t know how to post picture. Will let you know more when the family have tasted it.
Hi Freda, Hope you family loved it! For the filling, next time I would just give it a quick mix with electric beaters for a seconds. To pour the frosting without getting the plate messy, I would suggest putting the cake on the dish you will serve it on. Then take a few big squares of parchment paper and place them under the outer edges of the cake and covering the plate. Pour your frosting and smooth it around the cake as much as you can as it drips down. Excess messy frosting can then drip onto the parchment paper. Allow the frosting to set for a few minutes and then carefully pull out the parchment paper from around the edges of the cake and discard it, along with the frosting mess that may be on it. Hope that helps! I’d love to hear how everyone likes the cake 🙂
My name is freda Da costa I made this cake I left the mousse filling in the fridge overnight it was not to soft should I have best it up again also how do stop the plate getting messy when you pour the frosting how do I transfer my cake to a clean plate the cake looks lovely don’t know how to post picture
Really good! I’m entering in a baking contest. I hope it will win!
How fun! I’d love to hear how it goes!
I used the mousse and icing recipe to top a boxed cake mix that I made for my dad’s birthday. Absolutely delicious! The laying of the mousse topped with the icing made this dessert a special treat. Next time I will try the cake recipe from scratch.
Thank you.
Sounds delicious! So happy you enjoyed it. Thanks for sharing!
The cake & mousse filling were awesome; the warm chocolate filling tasted great! However the warm chocolate frosting, even if cooled to barely tepid, caused the mousse layer to melt and/or slide right off the cake, creating a disaster chocolate cak3 that tasted great. I don’t understand. What is the preferred temperature for the frosting to pour on the cake? I’d love to make this successfully.
Shocking! Made this as a goodbye cake to a close friend, after making the mousse and it being delicious I had high hopes for the actual cake but no! The cake was salty and absolutely disgusting, I actually could barely eat it! What a waste with such expensive ingredients!!! Absolutely terrible
I’m so sorry that your cake didn’t taste right. The cake recipe is just the Hershey’s brand “perfect chocolate cake” recipe. I’ve never had an issue with it and I’ve made it countless times (it also has amazing reviews on their website). I wonder if you used a different kind of salt, or possibly added too much salt.
Delicious!!! I have made this last night at my family party. and you know everyone was so happy to have this cake. Thaks for sharing it.
I saw this same recipe only the frosting ingredients are different. You use more butter and another recipe called for evaporated milk and vanilla extract. After making it, the frosting was delicious but too liquidy. I’m your opinion, does it matter if I use regular milk or evaporated ? And more butter and powered sugar?
Hi Felicia, using evaporated milk would be just fine. If you use evaporated milk you should not need to adjust the butter and powdered sugar. If it seems too runny in the future, make sure it has a chance to cool and set up and you could consider adding more powdered sugar!