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A piece of chocolate cake on a rustic set table.
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5 from 2 votes

Triple Chocolate Mousse Cake Recipe

This super moist triple chocolate mousse cake recipe combines unsweetened cocoa, dark cocoa, and semi sweet chocolate for a rich luscious flavor. Filled with fluffy chocolate mousse and covered with chocolate ganache this cake is a decadent trifecta in each bite.
Prep Time45 mins
Cook Time30 mins
Chilling Time4 hrs
Total Time5 hrs 15 mins
Course: Desserts
Cuisine: American
Keyword: cakes, chocolate mousse, desserts, triple chocolate mousse cake
Servings: 12
Calories: 605kcal


Chocolate Cake

  • 1 ¾ cup all-purpose flour
  • 1 and ¾ cups granulated sugar
  • ¼ cup unsweetened dark cocoa powder
  • ½ cups unsweetened cocoa powder
  • 2 teaspoons baking soda
  • 1 teaspoons baking powder
  • 1 teaspoon salt
  • ½ cup vegetable or canola oil
  • 2 large eggs room temperature
  • ¾ cups sour cream room temperature
  • ½ cup buttermilk room temperature
  • 2 teaspoons vanilla extract
  • ½ cup hot coffee or hot water

Chocolate Mousse Filling / Topping

  • ½ cup hot water
  • ½ cup unsweetened cocoa powder
  • 8 ounces quality semi sweet chocolate bars chopped
  • 2 cups heavy cream or heavy whipping cream
  • 2 Tablespoons powdered sugar confectioners sugar
  • ½ teaspoon vanilla extract

Chocolate Ganache

  • 8 ounces quality semi sweet chocolate bars finely chopped
  • 1 cup heavy cream


  • Make the cake
  • Preheat oven to 350 degrees F. Grease or spray 9X 13 pan with baking spray. Set aside.
  • Whisk flour, sugar, cocoa powders, baking soda, baking powder and salt together in a large bowl.
  • In a large bowl or stand mixer, mix the buttermilk, oil, sour cream, eggs and vanilla together until combined.
  • Add in dry ingredients and mix until combined. Add in hot coffee or water and beat until the batter in combined.
  • Pour into prepared 9 x 13 baking pan and bake for 30 to 40 minutes. Keep an eye out as baking times vary. The cake will be done when a toothpick inserted into the center of the cake comes out clean. (For a layered cake instructions see notes*)
  • Remove cake from oven and let cool completely on wire racks.

  • Prepare chocolate mousse filling / topping
  • As the cake cools, prepare the mouse so it can chill and be ready.
  • Whisk hot water and cocoa powder together in a bowl.
  • Place chopped chocolate bars in a double boiler to melt. You can also melt in the microwave by placing in a heat proof bowl and melting in 20 second increments. Stir after each increment until melted and smooth.
  • Pour melted chocolate into hot cocoa water mixture and stir in with silicone spatula until combined and smooth in texture.
  • In a stand mixer or with hand mixer. Beat heavy whipping cream, powdered sugar, and vanilla together on medium-high speed until medium peaks form. About 3 to 4 minutes.
  • Using a silicone spatula, gently fold chocolate mixture into the whipped cream until combine. Do not over mix or mix too hard so that the mousse does not deflate. Cover and refrigerate 2 hours until chilled (you can make this ahead of time up).
  • Prepare Chocolate Ganache
  • Place chopped chocolate in a medium heat proof bowl.
  • Heat cream in a small saucepan over medium heat until it begins to simmer gently (do not bring to a rapid boil). Pour over the chocolate and let it stand for 2 to 3 minutes to soften the chocolate. With a spatula stir until the chocolate is completely melted and smooth.
  • Let it cool at room temperature for 20 minutes. *If making layered cake and not 9 X 13 see notes for layered cake instructions.
  • Once the mixture is cooled pour over 9 X 13 cake and refrigerate for 1 hour.
  • After refrigerating spread mousse over the ganache layer and serve or refrigerate until serving.
  • Garnish with chocolate curls or sprinkles if desired.
  • Cover leftover cake tightly and store in the refrigerator for up to 5 days.


If you do not have dark chocolate cocoa you can use all regular unsweetened cocoa.

*Chocolate Mousse Layer Cake Instructions

To bake layer cake: Grease 2 to 4 - 8 or 9 inch round pans (depending on how many layers you want) lined with parchment. Then grease the parchment paper. Bake for 19 to 23 minutes for 4 cake layers and 23 to 26 minutes for 2 cake layers. Baking times vary with ovens so keep an eye on them. It is done when a toothpick inserted into the center comes out clean. Remove from oven and let cool on wire racks.
To assemble layer cake: Level cakes if desired by slicing with serrated knife or cake leveler. Place 1 cake layer on a cake stand. Using a large icing spatula place ⅓ of the chocolate mousse about ⅕ cups evenly on top. Then repeat with second and third cake. Top with 4th cake layer. Spready any remaining mouse around the outside of the cake for a crumb coat. Refrigerate cake for 1 to 4 hours to chill. Prepare Chocolate Ganache to ice outside of cake, as you wait. Pour or spoon ganache over chilled cake and smooth with a icing spatula and smooth the sides with a bench scraper.
Garnish with berries, chocolate curls and/or flowers as desired.
Can be served at room temperature or chilled. To chill place in refrigerator uncovered for 4 hours until served.
Store leftovers covered tightly in refrigerator for up to 5 days.


Serving: 1slice | Calories: 605kcal | Carbohydrates: 60g | Protein: 9g | Fat: 40g | Saturated Fat: 23g | Polyunsaturated Fat: 13g | Trans Fat: 1g | Cholesterol: 110mg | Sodium: 487mg | Fiber: 5g | Sugar: 37g