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
- Plum Cake
- 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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My son requested this cake for his birthday.This will be the third time making this cake, simple, elegant and delicous.
This is my go to never fail indulgent chocolate cake for special occasions (like Easter).I tend to wait till the frosting is cooler and thicker before I add it to the cake with a spatula
Hi I have used this recipe many times and it is amazing! but recently I have difficulty with the cake turning out crumbly and very moist and sunk in the middle! It was in the oven for 45 minutes.
I was wondering could I replace the flour and both leavening agents and use self raising flour instead. Would this solve the problem please?
Also the mousse texture once I take out of the fridge it isn’t smooth….how could I fix this please or do I need to wait for the chocolate mix to completely cool when adding to the cream and that could help?
Please advise thanks
Your “mousse ” is chocolate whip cream. Not a proper mousse. Thank you for crediting Hersheys for their cake recipe though.