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!

A slice of chocolate mousse cake on a plate.

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.

Two process photos for making homemade chocolate mousse.

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.

A baked chocolate cake round being cut in half, horizontally.

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.

A chocolate cake round on a plate with mousse added on top, then additional cake layers stacked, with mousse between each layer.

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.

Warm chocolate frosting being poured over a chocolate cake filled with chocolate mousse.

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.

A chocolate mousse cake with a slice removed from it.

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.

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Recipe

A slice of chocolate mousse cake on a plate.
Prep 40 mins
Cook 40 mins
Cool time 45 mins
Total 2 hrs 5 mins
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Equipment

  • Cake Pans

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

Chocolate cake recipe is the Hershey’s Chocolate cake
Make Ahead Instructions:
  • 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

Calories: 583kcalCarbohydrates: 85gProtein: 6gFat: 26gSaturated Fat: 12gPolyunsaturated Fat: 3gMonounsaturated Fat: 10gTrans Fat: 1gCholesterol: 56mgSodium: 357mgPotassium: 345mgFiber: 4gSugar: 66gVitamin A: 370IUVitamin C: 1mgCalcium: 106mgIron: 3mg

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*I first shared this recipe in May 2014. Updated May 2018 and February 2022.

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Lauren Allen

Welcome! I’m Lauren, a mom of four and lover of good food. Here you’ll find easy recipes and weeknight meal ideas made with real ingredients, with step-by-step photos and videos.

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Comments

  1. 5 stars
    Made this for a friend’s birthday–everyone raved about it! First time I ever cut layers to make a 4 layer cake–was nervous about that but it turned out great–I did end up with too much mousse and too much frosting, though.

  2. 5 stars
    Love this recipe it is my go to chocolate cake recipe always 🙂 I wanted to ask you if I could make this as a vanilla cake or is there a recipe you could recommend please

    Thanks

  3. 5 stars
    this is the BEST chocolate cake and mousse recipe I have ever tried. It will be the chocolate cake recipe forever!!

  4. 3 stars
    Tastes nice but too runny. I would advise to add cornflour to the egg mixture when heating up. This way it will help thicken when you add all the ingredients together. I added it add the end and even though I heated it gently with some cream, I have a pasty taste.

  5. 4 stars
    The cake and chocolate mousse were yummy! Not a fan of the chocolate frosting…was actually too sweet for my sweet tooth!

  6. I think the cake is good, moose not so much. I wish I only put 1/2 the chocolate in the whipping cream, it’s strong. Definitely not using chocolate frosting, I think it’s to much chocolate. Not sure I’ll even use the mousse.

  7. 5 stars
    Omg this is my favorite chocolate cake recipe!!! I made this twice already and it was a hit each time! Absolutely delicious and perfect chocolate cake. I’m definitely saving this as my go to!

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