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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This cake is AMAZING. My mom made it for my dad’s birthday while we are on vacation and we’ve had it the last two nights. It is So so good. I’ve never had a frosting like this, but I love it. We are going to be making this on a regular basis now! It’s a winner!
I made this and it was a hit!!!! Everything about it was delicious…..how would I convert this into cupcakes?
I have baked a number of cakes over the years and this is by far THE BEST recipe I have discovered. It was the first time a desert I made tasted like it came straight from a high class restaurant. I’ve made this cake several times and everyone who’s tried it is similarly blown away. It’s everything you want in a cake, rich but not super sweet and completely satisfying.
I tried this recipe twice, since the first time it was so good. But the second time, i realized that the first time I forgot to stir in the boiling water with the cake batter. I did do it the second time, but it ended up having to cook for a way longer time than it was supposed to. And, when I took them out of the pans, they were really under baked still. It ended up being a chocolate-y mess. This bugs me because the first time when I didn’t add the boiling water, it tasted fine.
Best Chocolate Mousse cake ever!! I made this for my daughters birthday and she was so happy. Everyone else loved it too!! I used buttermilk instead of milk, but followed the rest of the ingredients.
I made this last night for this evening’s dinner. As other comments this has a lot of ingredients . The issue I had was when I went to cut the cakes with serrated knife they slightly fell apart. I had let the cakes cool for a couple of hours so not sure what happened. The frosting was a little too thick but I made it work. The end result didn’t look too great but with the frosting I hid the flaws. I think next time I make it I won’t cut the cakes and just use two layers. It also did make a lot more mousse than what was needed. The taste was great as my family did enjoy the taste. I did not use chocolate chips and instead used baking chocolate bars (ghiradelli) instead. I will try again with my modifications as my family did enjoy it.
Do *NOT* use an 8 inch pan to bake the cakes. This cake requires a 9 inch pan at least. I used 8 inch pan and the batter rose and overflowed both pans in the oven and made a huge burned mess. I now have to clean my oven and grills. Apart from that, the cake was good. The recipe made more mousse than I needed – especially if applying it as in the photographs. Very rich and decadent. I decorated with maraschino cherries on top.
Somehow I suspect that you put all batter in one pan instead of dividing it into two parts. The recipe calls for two pan forms into which you divide the dough. And the amount of frosting is for two rounds baked separately. Please, clarify. Thank you.
Same thing happened to me. The next time, I use 8 inch pans, I will make 3 pans of cake batter or just go with 2, 9inch pans. Other than that, cake was delicious!
Just made it. Lots of ingredients went into this cake for it to completely taste like packated cake off the shelf. Sadly that was my very first impression. Really wanted to make something that was delicious.
On the other hand the cake is moist, almost like a mud cake.
I followed the recipe and the cake was delicious. After laying the mousse between the layers and on the top and sides of the cake, I decided not to make the chocolate frosting. I thought the cake looked and tasted great “as is” and didn’t need the additional ingredients- almost 4 cups of confectioner’s sugar and stick a butter. My husband had asked for a chocolate mousse cake for his b-day and we all loved the cake. When I divided each cake in two, I used plain dental floss as advised on another website and it was so easy.
Can you use melting chocolate instead of chocolate chips ?
Sure.
Hi, I’ve tried this recipe and it was delicious but I would like to know if you have an eggless option for the cake?
Lauren, thanks so much for your time in giving such explicit and detailed instructions for an amazing chocolate cake – only posting this because Sherry asked for an eggless version and my Vinegar & Oil Chocolate Cake fits the bill as it uses no eggs or dairy. Stir together 3 cups flour, 2 cups sugar, 9 Tblsp. unsweetened cocoa powder, 2 tsp. baking soda & 1 tsp. salt. Stir in – by hand – 1 cup vegetable oil, 1 Tblsp. apple cider vinegar & 1 tsp. vanilla extract (consistency will be VERY thick paste.). Stir in 2 cups water (1 cup at a time) just to batter consistency – okay for some lumps to remain. Divide between 2 prepared 9” cake pans and bake in preheated 375 oven for 20 – 25 minutes. Sounds weird, but this is my most requested cake recipe and one I used years ago in restaurant. HOWEVER, I’m addicted now to Lauren’s chocolate mousse and ganache frosting, and use them regardless of which cake recipe I make!