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I am obsessed with this Chocolate Mousse Cake because it hits every chocolate note I crave. The moist cake layer sings of rich cocoa, thanks to unsweetened cocoa powder, while the mousse is silk and dangerously airy from melted semisweet chocolate folded into cream.

I love how the chocolate whipped cream on top keeps it light enough to eat more than reason allows. Every bite melts, leaving that bittersweet hum that makes me pause.

But the best part is the texture play. Dense cake, fluffy mousse, pillowy whipped cream.

I want another slice right now. No apologies.

I want more.

Ingredients

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All-purpose flour: gives structure and that tender crumb you’ll eat fast.
Granulated sugar: sweetness and keeps cake moist, simple and reliable.
Unsweetened cocoa: deep chocolate taste, not too sweet, slightly bitter.
Baking powder: lifts the cake, makes it light and springy.
Baking soda: helps rise and browns the crust nicely.
Salt: balances sweetness and rounds out the chocolate flavor.
Eggs: bind everything together, add richness and a little protein.
Whole milk: adds fat and tenderness, makes crumb soft.
Vegetable oil: keeps cake moist days later, no weird flavors.
Vanilla extract: warmth and subtle sweetness, it just makes it homey.
Boiling water: blooms cocoa for intense chocolate, makes batter smooth.
Semisweet chocolate: melty, rich base for the mousse, bold chocolate hit.
Heavy cream (to melt): loosens chocolate, makes that silky mousse texture.
Heavy cream (to whip): airy lift, lightens mousse into clouds.
Powdered sugar (mousse): sweetens gently without graininess, blends smoothly.
Vanilla (mousse): soft background note, keeps chocolate from tasting flat.
Heavy cream (whip): pillow-top topping, makes each slice feel fancy.
Powdered sugar (whip): sweetens whipped cream without gritty bits.
Cocoa powder (whip): adds chocolate depth and a little bitterness.
Vanilla (whip): rounds the cream, makes it taste homemade.
Chocolate shavings: pretty finish, adds texture and chocolate crunch.
Cocoa dusting: simple, dramatic look and a touch of bitterness.

Ingredient Quantities

Chocolate cake: 1 3/4 cups (220 g) all purpose flour

Chocolate cake: 2 cups (400 g) granulated sugar

Chocolate cake: 3/4 cup (75 g) unsweetened cocoa powder

Chocolate cake: 1 1/2 teaspoons baking powder

Chocolate cake: 1 1/2 teaspoons baking soda

Chocolate cake: 1 teaspoon salt

Chocolate cake: 2 large eggs

Chocolate cake: 1 cup (240 ml) whole milk

Chocolate cake: 1/2 cup (120 ml) vegetable oil

Chocolate cake: 2 teaspoons vanilla extract

Chocolate cake: 1 cup (240 ml) boiling water

Chocolate mousse: 8 ounces (225 g) semisweet or bittersweet chocolate, finely chopped

Chocolate mousse: 2 cups (480 ml) heavy cream, divided (about 1/2 cup to melt chocolate, 1 1/2 cups to whip)

Chocolate mousse: 2 tablespoons powdered sugar

Chocolate mousse: 1 teaspoon vanilla extract

Chocolate whipped cream: 1 1/2 cups (360 ml) heavy cream

Chocolate whipped cream: 2 to 3 tablespoons powdered sugar

Chocolate whipped cream: 2 tablespoons unsweetened cocoa powder

Chocolate whipped cream: 1 teaspoon vanilla extract

Garnish and finishing: chocolate shavings or cocoa powder for dusting, optional

How to Make this

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1. Preheat oven to 350°F (175°C). Grease and line a 9 inch round cake pan.

2. In a large bowl whisk together 1 3/4 cups (220 g) all purpose flour, 2 cups (400 g) granulated sugar, 3/4 cup (75 g) unsweetened cocoa powder, 1 1/2 teaspoons baking powder, 1 1/2 teaspoons baking soda, and 1 teaspoon salt.

3. Add 2 large eggs, 1 cup (240 ml) whole milk, 1/2 cup (120 ml) vegetable oil, and 2 teaspoons vanilla extract to the dry ingredients and beat until combined. Stir in 1 cup (240 ml) boiling water until batter is smooth (batter will be thin).

4. Pour batter into prepared pan and bake 30 to 35 minutes or until a toothpick inserted into the center comes out with a few moist crumbs. Cool in pan 10 minutes, then transfer to a wire rack to cool completely.

5. Make the chocolate mousse: place 8 ounces (225 g) finely chopped semisweet or bittersweet chocolate in a heatproof bowl. Heat 1/2 cup (about 120 ml) of the heavy cream until just simmering and pour it over the chocolate. Let sit 1 minute, then stir until smooth. Let chocolate mixture cool to room temperature.

6. Whip the remaining 1 1/2 cups (360 ml) heavy cream with 2 tablespoons powdered sugar and 1 teaspoon vanilla extract to soft peaks. Fold one third of the whipped cream into the cooled chocolate to lighten, then gently fold in the remaining whipped cream until fully combined and fluffy.

7. Level the cooled cake if needed, place on a serving plate, and spread the chocolate mousse evenly over the cake. Chill the cake in the refrigerator for at least 2 hours or until mousse is set.

8. Make the chocolate whipped cream topping: whip 1 1/2 cups (360 ml) heavy cream with 2 to 3 tablespoons powdered sugar, 2 tablespoons unsweetened cocoa powder, and 1 teaspoon vanilla extract to stiff peaks.

9. Remove chilled cake from refrigerator, pipe or spread the chocolate whipped cream over the set mousse layer, garnish with chocolate shavings or a dusting of cocoa powder if desired, and return to the refrigerator until ready to serve.

Equipment Needed

1. Oven
2. 9 inch round cake pan lined with parchment paper
3. Mixing bowls (large and medium)
4. Measuring cups and spoons
5. Whisk and rubber spatula
6. Electric mixer or hand mixer
7. Heatproof bowl and small saucepan (or microwave) for melting chocolate
8. Wire cooling rack
9. Offset spatula or piping bag for topping and finishing

FAQ

Can I make the cake and mousse ahead of time? Yes. Bake the cake up to 2 days ahead and keep it tightly wrapped at room temperature or refrigerated. Make the mousse and refrigerate in an airtight container up to 2 days. Assemble the cake the day you serve for best texture.

How do I melt the chocolate for the mousse without seizing it? Warm about 1/2 cup of the cream until just simmering, pour it over chopped chocolate, let sit 1 minute, then stir gently until smooth. If needed, warm a few additional teaspoons of cream to loosen, but avoid boiling.

Can I use a different type of chocolate for the mousse? Yes. Semisweet or bittersweet are recommended for balance. Milk chocolate will be sweeter and softer, while very dark chocolate will be more intense. Adjust powdered sugar in whipped components to taste.

How do I prevent the whipped cream from becoming grainy or overwhipped? Chill the bowl and beaters, use cold heavy cream, and whip at medium speed. Stop when soft peaks form if folding into mousse, or firm peaks for piping. If overwhipped, gently fold in a tablespoon of cold cream to smooth it.

What is the best way to assemble the mousse cake so edges are clean? Level the cake layers, place one on a cake board, spread a thin crumb coat of mousse, add the second layer, then pipe or spread the remaining mousse and whipped cream. Chill 30 to 60 minutes between steps to set layers and get clean edges when finishing.

How should I store leftovers and how long will they keep? Store the assembled cake covered in the refrigerator for up to 3 days. For longer storage, freeze slices wrapped tightly; thaw overnight in the refrigerator before serving.

Chocolate Mousse Cake Recipe Substitutions and Variations

All purpose flour: substitute with cake flour (use 2 cups minus 4 tablespoons cake flour for every 1 3/4 cups AP flour for a lighter crumb); or use 1:1 gluten free all purpose blend if gluten free is needed, no extra adjustment.
Granulated sugar: substitute with light brown sugar for a moister cake and slight caramel note, use 1:1 but reduce liquid by 1 to 2 tablespoons; or use coconut sugar 1:1 for a less refined option, flavor will be deeper.
Unsweetened cocoa powder: substitute with Dutch processed cocoa for a smoother, less acidic chocolate flavor, use 1:1 but omit baking soda or reduce it if recipe relies on natural cocoa acid; or use equal part melted dark chocolate and reduce some fat in batter accordingly.
Heavy cream (for mousse and whipped cream): substitute for mousse with chilled full fat coconut cream (same volume) for dairy free mousse; for whipped cream topping use stabilized whipped cream made from 1:1 whipping cream substitute such as aquafaba (whip 3 tablespoons aquafaba per 1/4 cup heavy cream equivalency with 1 to 2 tablespoons powdered sugar) for a vegan option.

Pro Tips

1) Sift the flour and cocoa together before mixing. It helps prevent lumps, keeps the batter uniform, and gives the cake a finer crumb.

2) Boost the chocolate flavor by using strong hot coffee instead of plain boiling water. The liquid still thins the batter, but coffee makes the chocolate taste deeper without tasting like coffee.

3) When making the mousse, pour the hot cream over the chopped chocolate and let it sit until the chocolate has softened before stirring. Cool the ganache to warm room temperature before folding in whipped cream so the mousse stays light and airy.

4) Keep everything cold for the whipped toppings: chill the bowl and beaters, and use very cold cream. If you need a more stable topping for slicing ahead of time, add a teaspoon of instant pudding mix or a teaspoon of dissolved gelatin to the whipping cream.

Chocolate Mousse Cake Recipe

Recipe by Nikoli Athen

0.0 from 0 votes

Servings

servings

Calories

682

kcal

Equipment: 1. Oven
2. 9 inch round cake pan lined with parchment paper
3. Mixing bowls (large and medium)
4. Measuring cups and spoons
5. Whisk and rubber spatula
6. Electric mixer or hand mixer
7. Heatproof bowl and small saucepan (or microwave) for melting chocolate
8. Wire cooling rack
9. Offset spatula or piping bag for topping and finishing

Ingredients

Chocolate cake: 1 3/4 cups (220 g) all purpose flour
Chocolate cake: 2 cups (400 g) granulated sugar
Chocolate cake: 3/4 cup (75 g) unsweetened cocoa powder
Chocolate cake: 1 1/2 teaspoons baking powder
Chocolate cake: 1 1/2 teaspoons baking soda
Chocolate cake: 1 teaspoon salt
Chocolate cake: 2 large eggs
Chocolate cake: 1 cup (240 ml) whole milk
Chocolate cake: 1/2 cup (120 ml) vegetable oil
Chocolate cake: 2 teaspoons vanilla extract
Chocolate cake: 1 cup (240 ml) boiling water
Chocolate mousse: 8 ounces (225 g) semisweet or bittersweet chocolate, finely chopped
Chocolate mousse: 2 cups (480 ml) heavy cream, divided (about 1/2 cup to melt chocolate, 1 1/2 cups to whip)
Chocolate mousse: 2 tablespoons powdered sugar
Chocolate mousse: 1 teaspoon vanilla extract
Chocolate whipped cream: 1 1/2 cups (360 ml) heavy cream
Chocolate whipped cream: 2 to 3 tablespoons powdered sugar
Chocolate whipped cream: 2 tablespoons unsweetened cocoa powder
Chocolate whipped cream: 1 teaspoon vanilla extract
Garnish and finishing: chocolate shavings or cocoa powder for dusting, optional

Directions

Preheat oven to 350°F (175°C). Grease and line a 9 inch round cake pan.
In a large bowl whisk together 1 3/4 cups (220 g) all purpose flour, 2 cups (400 g) granulated sugar, 3/4 cup (75 g) unsweetened cocoa powder, 1 1/2 teaspoons baking powder, 1 1/2 teaspoons baking soda, and 1 teaspoon salt.
Add 2 large eggs, 1 cup (240 ml) whole milk, 1/2 cup (120 ml) vegetable oil, and 2 teaspoons vanilla extract to the dry ingredients and beat until combined. Stir in 1 cup (240 ml) boiling water until batter is smooth (batter will be thin).
Pour batter into prepared pan and bake 30 to 35 minutes or until a toothpick inserted into the center comes out with a few moist crumbs. Cool in pan 10 minutes, then transfer to a wire rack to cool completely.
Make the chocolate mousse: place 8 ounces (225 g) finely chopped semisweet or bittersweet chocolate in a heatproof bowl. Heat 1/2 cup (about 120 ml) of the heavy cream until just simmering and pour it over the chocolate. Let sit 1 minute, then stir until smooth. Let chocolate mixture cool to room temperature.
Whip the remaining 1 1/2 cups (360 ml) heavy cream with 2 tablespoons powdered sugar and 1 teaspoon vanilla extract to soft peaks. Fold one third of the whipped cream into the cooled chocolate to lighten, then gently fold in the remaining whipped cream until fully combined and fluffy.
Level the cooled cake if needed, place on a serving plate, and spread the chocolate mousse evenly over the cake. Chill the cake in the refrigerator for at least 2 hours or until mousse is set.
Make the chocolate whipped cream topping: whip 1 1/2 cups (360 ml) heavy cream with 2 to 3 tablespoons powdered sugar, 2 tablespoons unsweetened cocoa powder, and 1 teaspoon vanilla extract to stiff peaks.
Remove chilled cake from refrigerator, pipe or spread the chocolate whipped cream over the set mousse layer, garnish with chocolate shavings or a dusting of cocoa powder if desired, and return to the refrigerator until ready to serve.

Notes

Below you’ll find my best estimate of this recipe’s nutrition facts. Treat the numbers as a guide rather than a rule—great food should nourish both body and spirit. Figures are approximate, and the website owner assumes no liability for any inaccuracies in this recipe.