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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can the frosting be made with out cocoa powder and used white or with food coloring to cover any cake? Like a faux fondant?
Hi Diana, Try this for the frosting:
½ cups Butter
¼ cups Milk
3-½ cups Powdered Sugar
1 teaspoon Vanilla Extract
(Add more powdered sugar if you need a thicker consistency!)
Sounds yummy!
In a small saucepan bring the butter and milk to a boil. Add the remaining ingredients to a separate mixing bowl. Once the milk and butter are boiling, pour over the other ingredients in the mixing bowl. Stir until well mixed. Add more powdered sugar if you need a thicker consistency.
thanks will give it try!!!
I just made this cake , I was sitting in the dining room noticed smoke in the kitchen . I opened the stove door too see why I had smoke the cake both pans over flowed all over in the oven and now a house full of smoke . What could of happen ???????????? I followed the directions as said . I won’t be trying this one again !!!!!!!!
I wonder if you used too much baking soda?
That is what it sounds like to me.
Quick question. can this cake be left out for a period of time. especially with the mousse having heavy cream. Thank you so much.
Hi Sharon, It would be fine for an hour or two, but it’s best to store it covered in the refrigerator! 🙂
Is it unsweetened cocoa powder we use?
Yes! Unsweetened Cocoa Powder
I was out of milk for the frosting and used almond milk…not the same, weirdest frosting ever. Ha ha! Otherwise, a yummy cake though 🙂
This review will be broken into three components: pros, cons, and what I would do differently next time.
Pros: the cake, icing, and mousse are FABULOUS. So delicious and packed-full of flavor. The recipe was easy to follow and practically fool-proof. I’ve been baking for 15 years, but anybody could do this without too many serious blunders. Just remember to make sure you’ve added every ingredient into the mixing bowl and you’re good to go. Now with all of that being said. . .
the cons: Just because the cake, icing, and mousse are delicious, it does not mean they go well together. If you are a die-hard chocolate fan you’ll probably have very little complaints about the taste. To me the chocolate was entirely too overpowering and the texture of the cake, mousse, and icing just didn’t mesh well together.
what I would do next time: Baking this was definitely a learning experience, ha. Number one, I would make sure the cakes were cooled entirely. Cut them in half and place them in the fridge if they’re even remotely warm. I had some semi-warm cake at some point and it melted the mousse a little too much for my liking. Seems like an obvious tip, but it was something I didn’t take into consideration. Second, I would ditch the icing and just use the mousse for the filling and a little bit on top. Or, just keep mousse as a filler and sprinkle some powdered sugar on top. That way the chocolate isn’t too overbearing. Third, if I were to use the icing I’d ditch the mousse and instead use a jelly-like or vanilla cream filling. Let the icing harden a little bit, too. I wasn’t a fan of straight up pouring the icing on the cake. Just made a mess that I had to wait to solidify a little and then go back through and “fix” it up with an icing knife.
Overall I give this cake (with the icing and mousse combined) a 5/10. If the icing, mousse, and cake were being rated separately I would give them each 10/10. Just a bit too weird of a combo for me.
Hi Lauren,
I loved this cake recipe!! The cake was soft and moist, just the way I like it!! I had some issues getting it out of the cake pans intact (my fault I am sure), so I didn’t try the mousse filling, but the cake was just delicious even without the topping. My pie loving husband even loved it as well! Thanks so much!!
Hello Lauren!!!
First of all, I absolutely loveeeeeddd this recipe!!! My aunt loves Chocolate ….Especially Chocolate mousse!! I knew that this would be a dream cake for her birthday. I am an home cook and amateur baker. So, this was my first time actually baking a cake where I had to crumb coat and fully frost. To my surprise, it came out excellent and I was truly proud of myself.
Thank so much, I’m glad you liked it!
29th December 2014
I tried this amazing cake it was awesome thanks Lauren it was wonderful baking. My kids anxious waited to eat it.
I had a question, I’m making this tonight to have for someone’s birthday tomorrow, so I hope for a quick reply! I only have 1 round pan, can I bake the one, and then bake the other after the cake has been cooled/removed? Will the batter be okay just sitting out while the other layer bakes? Thanks! Looks soooo delicious, can’t wait to try this!!
Hi Rachel, it’s not ideal to do it that way, but I will admit that I’ve done it before and it turned out just fine! You could over the mixing bowl with a wet towel and refrigerate the batter while the first cake bakes! Good luck–hope you love it!! 🙂
I ended up just buying another pan! 🙂 This cake was a little challenging for a beginner, but very much worth it. Everyone LOVED it! I had a whole container of the mousse filling leftover, so I put it in the fridge overnight. And wow! It set up beautifully, and was a nice treat! 🙂