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 you use buttercream icing on cake instead?
Yes, sure!
Just made the cake and have lots of mousse filling left over – any ideas how I can use it up or if I can freeze it for when I make the cake again? Thanks!!
I made the cake the other day and everything worked out perfectly. The cake was nice and moist, and came out of my Pam’s no problem, I only used grease and flour.
I went to make another one more recently and I opened the oven to find that my batter had gone over the edges and the center didn’t seem done still. Anyone have any suggestions or insights?
I’ve made the Hershey’s chocolate cake several times and love it. Made it tonight with buttermilk instead of milk and it turned out weird… It was dense add chewy… Not great. I don’t recommend using buttermilk here!
The rest of the parts were great!
Very disappointed. Made the cake and followed instructions. Cakes looked fine when came out the oven. They looked OK when I cut them in half. But once I stocked them on top of each other with the mousse in the middle, the cakes started to crumble badly and completely broke off into a huge mess. I put a lot of effort into this. My friend bought the ingredients for me because I’m avoiding going to the store during the Coronavirus. My daughter asked for this cake for her birthday and now I don’t have a cake for her and will have to bake something very basic for her birthday with whatever ingredients are left in my pantry. I buttered the pans and floured them. The cake didn’t stick and seemed fine. The problem was that the cake crumbled and big parts of it broke off after laying it. Big mess. I had to toss it all out. If you are considering baking this cake, consider again. I wish I read the reviews before deciding to make this.
Made cake and mousse last night and refrigerated. Making frosting in a bit and then assembling. Question— do I leave mousse get to room temp first before spreading?
Thanks. Can’t wait to try a piece!
You don’t need to let the mouse come to room temperature. Enjoy!
I Used parchment paper and then sprayed it with Bakers Joy and did not have any trouble at all with the cake coming out… It was absolutely delicious and a big hit. It will become one of my favorite go-to desserts.
I also had trouble with my cake layers sticking to the pan. I threw away the first cake. I’ll make it again with the mousse filling and frosting. But I will use a more reliable recipe for the cake itself.
Line your pans with parchment paper and then spray them lightly with cooking spray.
I made this for my husband’s birthday this past weekend and I could NOT believe how DELLLLICIOUS and MOIST it was! Its incredible. I made the cake Friday, used parchment and spray with no issues. I tasted tiny bits that fell off and was a bit disappointed…just kinda tasted normal, nothing special. I let it sit in the fridge until Saturday evening when I put it all together and WOW! The cake part was incredible, the mousse was my husband’s favorite part, and the frosting my daughter’s fav. Will FOR SURE make this again! THANK YOU!
I have made this cake recipe for years, and it has always come out perfectly. Do you live at a higher elevation where adjustments need to be made? I use Crisco to grease pan, add waxed paper circle (and grease it), then flour the whole pan.
I made the mousse filling for a smash cake. It was delicious. Don’t skimp on the sugar. I did at first since it’s for a baby. And the chocolate was too bitter. Added the sugar and it balance it right out.
Thanks for sharing!
I was so excited to make this cake. Prepared pans exactly how in recipe, but when I tried to remove cake from pan the cake broke in half and fell completely apart. I’ve never had a cake do that before. So crumbly that it doesn’t seem to want to stay together. It’s weird because its seems moist at the same time. Not sure what happened, very disappointed.
If you try to turn a cake out straight away it will break. Leave it in the tin to cool for 5 to 10 minutes before turning it out
What kind of milk should be used for the cake and frosting? Whole milk? Thanks it looks delicious!
I would NOT use skim milk, but any other kind will work. Whole milk or 2% would be delicious.