Mama’s Very Chocolate Mousse Cake

Chocolate Mousse Cake

Dark, fudgy chocolate cake. Light, creamy chocolate mousse. It’s the perfect cake.

For some helpful tips before you begin, click here.


For the cake:

  • 1 cup (106 g) unsweetened cocoa powder
  • 1/3 cup (75 g) semi-sweet or bittersweet chocolate, finely chopped
  • 1 teaspoon (2 g) instant coffee
  • 1 1/2 cups (360 ml) very hot water
  • 2 cups (240 g) cake flour
  • 1 teaspoon (4 g) baking powder
  • 1 teaspoon (5 g) baking soda 
  • 3/4 teaspoon (4.5 g) fine salt
  • 2 cups (400 g) granulated sugar
  • 2 large eggs
  • 1 cup (240 ml) buttermilk
  • 1/2 cup (120 ml) vegetable oil
  • 1 tablespoon (15 ml) vanilla extract

For the mousse:

  • 1 1/4 cup (200 g) semi-sweet chocolate chips
  • 1 1/4 cup (200 g) milk chocolate chips
  • 1/2 cup (120 ml) boiling water
  • 1/4 cup (22 g) cocoa
  • 2 1/2 cups (600 ml) heavy cream
  • 2 tablespoons (15 g) powdered sugar
  • 1 teaspoon (5 ml) vanilla extract

For the chocolate shell drizzle:

  • 2 tablespoons (20 g) milk chocolate chips
  • 3 tablespoons (30 g)) bittersweet chocolate chips
  • 2 tablespoons (27 g) refined coconut oil
  • 1/8 teaspoon (.5 ml) vanilla extract



1. Preheat the oven and prepare the baking pans.

– Preheat the oven to 350°F (177°C) (325°F or 163°C for dark or glass pans).
– Place the oven rack in the middle position.
– Spray two 9-inch baking pans with cooking spray.
– Line the pans with parchment paper. Coat the parchment paper with cooking spray as well.

2. Melt and combine the chocolate and cocoa.

– Place the cocoa, chopped chocolate and instant coffee in a small heat-proof bowl.
– Pour in the very hot water.
– Stir until everything is melted and smooth. Set aside.

3. Sift and combine the dry ingredients.

– In a medium bowl, sift together the flour, baking soda, baking powder and salt.
– Briefly stir with a whisk to evenly combine. Set aside.

4. Combine the wet ingredients.

– In a large bowl, whisk together the sugar, eggs, buttermilk, vegetable oil and vanilla extract until combined and smooth.
– Add the cocoa mixture and stir until combined and smooth.
– Scrape the sides and bottom of the bowl with a rubber spatula to ensure everything is evenly combined and there are no streaks of unmixed batter.

5. Combine the dry and wet ingredients.

– Add the dry ingredients into the wet ingredients and stir gently with a whisk just until combined and smooth.
– Scrape the sides and bottom of the bowl with a rubber spatula to ensure everything is evenly combined and there are no streaks of unmixed batter.
– The batter will be runny.

6. Pour the batter evenly into the baking pans and bake.

– Pour the batter evenly between the two pans.
– Tap the pans firmly on the countertop to release any air bubbles.
– Bake for about 30 minutes, or until an inserted toothpick comes out clean with a some moist crumbs attached.
– Do not overbake or the cake will be dry.

7. Cool the cakes before filling or frosting.

– Allow the cake to cool in the pan for about 30 minutes before turning them out on to cooling racks.
– Cool completely before filling or frosting.

  • If not making the cake right away, wrap the cooled cakes snugly in plastic wrap. Place in a freezer bag and freeze for up to one month. When ready to use, let thaw still wrapped at room temperature.


1. Make the melted chocolate base.

– Place all the chocolate chips in a microwave-safe bowl. Melt at 50% power in 30 second bursts, stirring in between bursts, until melted and smooth. Set aside.
– Stir the boiling water and cocoa together until completely combined.
– Pour the hot water/cocoa mixture into the melted chocolate and stir until combined and smooth.
– Set aside and let cool completely to room temperature.

2. Whip the cream.

– Beat the heavy cream, powdered sugar and vanilla on low speed until combined.
– Increase the speed and beat the cream to medium-stiff peaks.

3. Combine the melted chocolate base and whipped cream.

– Fold about one-third of the whipped cream into the cooled melted chocolate until only a few white streaks remain.
– Gently fold in another third of the whipped cream until only a few white streaks remain. Be sure to scrape the sides and bottom, too, for even mixing.
– Finally fold in the remaining whipped cream until there are no more white streaks and the mousse is evenly combined.

4. Chill for 2 hours before using.

– Cover the mousse with plastic wrap and refrigerate for at least 2 hours and up to 2 days before using.


1. Slice each cake into two layers.

– If the cake is mounded on top, Use a thin, smooth-edged knife to level it out.
– Carefully slice the cakes into two layers each.

  • Use a very long smooth-edged knife or a long piece of dental floss. (See TIPS)

2. Spread chocolate mousse in between the cake layers.

– Lay the bottom layer on the cake stand or plate.
– Fold the mousse a bit and then spread about 1 1/2 cups mousse over the entire layer. (See TIPS)
– Repeat with the remaining layers.

  • There should be enough mousse to spread 1 1/2 cups between each layer of cake, including the top.

– Use any remaining mousse to fill and smooth out the sides of the cake.
– Place the chocolate mousse cake in the refrigerator to chill for at least 30 minutes.
– Meanwhile, make the chocolate shell drizzle.


1. Make the chocolate shell.

– Place the milk chocolate chips, bittersweet chocolate chips and refined coconut oil in a microwave-safe bowl.
– Melt in the microwave at 50% power in 15 second bursts, stirring in between bursts until melted and smooth.
– Cool to room temperature.

2. Drizzle the chocolate shell on the cake.

– Drizzle the cooled chocolate shell decoratively on top of the mousse cake.
– Place the cake back into the refrigerator until ready to serve.

Serving the cake:

– For the neatest slices, cut the cake while fully chilled.
– For the softest mousse cake experience, let the cake sit at room temperature for a bit before eating.

Storing the cake:

– This cake should be covered and refrigerated.
– Cover cut or exposed edges of the chocolate mousse cake with plastic wrap or a piece of wax paper to prevent the cake from drying or forming a crust.


chocolate mousse cake


This chocolate cake has a fine, soft, tender crumb. It is very moist. And the use of both cocoa and chocolate adds depth. And the chocolate mousse uses both milk and semi-sweet chocolate for balance plus a bit of cocoa for an extra hit of chocolate.


Here are 6 helpful tips:

1) Good quality cocoa and chocolate is a must!

– This recipe can use either natural cocoa or Dutch-processed cocoa.

  • You don’t need to buy the most expensive brand. You do need to buy a brand you love. I personally prefer to use Dutch-processed cocoa because of it’s darker color and less acidic flavor. Find your preference!

– Use chocolate that you would love to eat.

  • Better tasting chocolate, better tasting chocolate mousse cake!

2) The coffee enhances the flavor of the chocolate.

– The taste of the coffee itself is indiscernible. But if you are very sensitive to the taste of coffee and do not like it, you can skip it.

3) Once you mix the dry ingredients and wet ingredients for the cake, don’t let the batter sit.

– The baking soda will lose its efficacy the longer it sits and your cake will not rise as it should. So once you mix your dry and wet ingredients, ignore everything else and get your batter into the pans and into the oven.

4) Do not overbake the cake.

– The baking times given in any recipe is just a reference. Ovens vary. Once you can smell the cake baking from the oven, it is a good idea to start looking in on it. Otherwise, start checking about 5 minutes before the indicated time.

– The cake should look dry on top and the sides of the cake should be just beginning to pull away from the sides of the pan. The top should spring back when lightly tapped, but should still feel soft. And an inserted toothpick should come out clean with maybe a few moist crumbs attached.

5) Slicing the cake into layers with dental floss.

The easiest way for me to split a cake into even layers is with dental floss.
– Cut a piece of unflavored dental floss long enough to go around the entire cake plus an extra 10 to 12 inches.
– Carefully place the floss around the cake at the middle point where it should be split. Be sure to check and make sure the entire piece of floss is situated at the middle point.
– Criss-cross the ends of the floss and pull outward until the floss has cut through the entire cake.

6) Spreading the mousse layers:

When spreading the mousse onto layers of cake, drop tablespoons of mousse around the cake and then gingerly connect the dots of mousse. This should help prevent pulling up cake crumbs while spreading the mousse into an even layer.

slice of chocolate mousse cake side

Click here to read more about Cake Basics.

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