Chocolate Mousse Cake Recipe

Two layers of chocolate cake are filled with creamy chocolate mousse and covered with chocolate ganache. It doesn't get any more decadent than this.

Close-up overhead view of a chocolate mousse cake, decorated with chocolate curls and dusted with confectioner's sugar.

Serious Eats / Yvonne Ruperti

Why It Works

  • The mousse is made with a cooked, custard-like base, which results in a rich, full-flavored filling while eliminating the food safety concerns associated with raw-egg mousse recipes.
  • Espresso powder adds a complementary depth to the chocolate cake.
  • Using semi-sweet chocolate makes forming the chocolate curls much easier.

Chocolate mousse cake and I have a special kind of thing. I fell in love with this cake at a restaurant during one of my waitressing jobs—it was long before I knew I even wanted to go to culinary school to be a pasty chef. An outrageously sinful chocolate mousse cake was on the menu: layers of moist chocolate cake and creamy chocolate mousse, all piled high with chocolate shavings. Even though it came delivered in a box, frozen and already sliced, I set my sights on a slice of it every night (it didn't help that it was my job to present our dessert tray). However, I wouldn't sit down at a table at the end of my shift, relax, and eat it properly. No, that's what an advanced human would do. I'd shove it in a take out bag, then use one hand to cram it into my face while the other hand drove my car home. My steering wheel was perpetually smeared with chocolate.

Swathed in a shiny chocolate ganache with a pile of delicate chocolate curls on top, this cake is a total showstopper. And what's lying within does not disappoint. Two layers of chocolate cake sandwich a deep, thick layer of insanely decadent egg-enriched chocolate mousse. But it's all copacetic: the eggs in this mousse are cooked. How? By heating them up in a cooked vanilla sauce-like base.

Though the chocolate curls may look intimidating, they're really not hard at all (and dare I day, fun?). The best part is that you don't even have to temper the chocolate. For the chocolate curls, I find that semi-sweet chocolate, or even a lesser quality chocolate, is the easiest to work with. Even if you wind up with shards of chocolate instead of tight rolls, it'll look amazing with the snowy dusting of sugar over the top. Everyone will be dying to know where you bought it.

One final note: This cake is easiest if made over the course of 2 days. Bake the cake and fill it with mousse the first day; cover with ganache the second.

December 2012

Recipe Facts

Active: 90 mins
Total: 6 hrs
Serves: 16 servings

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Ingredients

  • 3/4 cup (3 3/4 ouncesall-purpose flour

  • 1/3 cup (3/4 ouncecocoa powder

  • 3/4 teaspoon baking soda

  • 1/2 cup plus 2 tablespoons (about 4 1/3 ounces) packed light brown sugar

  • 2/3 cup sour cream

  • 1/3 cup vegetable oil

  • 1 large egg

  • 1 teaspoon instant espresso powder

  • 2 teaspoons pure vanilla extract, divided

  • 1/4 teaspoon salt

  • 1/3 cup (2 1/3 ouncesgranulated sugar

  • 3 large egg yolks

  • 2 3/4 cups plus 2 tablespoons heavy cream, cold, divided

  • 20 ounces bittersweet chocolate, finely chopped, divided

  • 4 ounces semisweet chocolate, finely chopped

  • Confectioners' sugar for dusting cake

Directions

  1. Adjust oven rack to middle position and preheat oven to 350°F (175°C). Line a 9-inch springform pan with parchment and spray with nonstick pan spray.

  2. Sift flour, cocoa, and baking soda in a small bowl; set aside. In a medium bowl, whisk brown sugar, sour cream, oil, egg, espresso powder, 1 teaspoon vanilla, and salt until combined. Whisk in dry ingredients until smooth.

  3. Spoon batter into prepared pan and bake until just firm and a toothpick inserted into center comes out clean, 17 to 19 minutes. Transfer pan to wire rack to cool 20 minutes, then remove cake from pan to cool completely, about 1 hour.

  4. In a small bowl, whisk granulated sugar with yolks. In a medium saucepan over medium heat, bring 1/2 cup cream to simmer. Slowly whisk hot cream into egg mixture, then return entire mixture to saucepan. Cook over medium-low heat, stirring, until mixture just thickens, about 1 minute. Whisk in 1 teaspoon vanilla and 12 ounces bittersweet chocolate until smooth. Transfer to a large bowl and let cool to room temperature, about 45 minutes.

  5. Using a stand mixer or hand mixer fitted with whip attachment, whip 1 1/2 cups cream to medium peak. Fold 1/3 of whipped cream into cooled chocolate mixture until combined and smooth. Fold in remaining whipped cream just until no white streaks remain.

  6. Line bottom and sides of springform pan with plastic wrap. When cake is cool, slice into two layers. Place one layer into bottom of pan. Fill with mousse and smooth top. Place second layer on top and gently press to adhere. Cover and chill until set, at least 3 hours.

  7. Place remaining 8 ounces bittersweet chocolate in a medium bowl. In a small saucepan, heat remaining 3/4 cup plus 2 tablespoons cream until simmering. Pour over chocolate and let sit 5 minutes. Whisk until smooth.

  8. Remove sides of springform pan and invert cake onto a large plate. Peel off plastic wrap and replace bottom of springform pan. Invert onto wire rack and set rack into rimmed baking sheet. Pour ganache over cake, allowing it to drip over sides. Chill until set, about 30 minutes. Using an offset spatula, spread any remaining ganache around the sides of cake.

  9. Melt semi-sweet chocolate in microwave or in pan over bowl of barely simmering water. Spread chocolate onto back of flat baking sheet (chocolate should be spread very thin). Chill briefly until just set.

  10. Holding bench scraper at 45-degree angle, scrape 2 to 3-inch wide strips of chocolate until it forms a curl. If chocolate is breaking, it is too cold; let it warm up slightly (see notes). Place curls on cake and dust with confectioners' sugar. Allow cake to warm up slightly at room temperature before serving for the creamiest texture and best chocolate flavor.

Special Equipment

9-inch springform pan, stand mixer or hand mixer

Notes

If chocolate is not forming nice curls, simply make large shards to decorate cake.

Make-Ahead and Storage

This cake is easiest if made over the course of 2 days. Bake the cake and fill with mousse the first day; cover with ganache the second. Chocolate curls can be made ahead and kept wrapped and stored in a cool, dry, place.

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Nutrition Facts (per serving)
521 Calories
39g Fat
34g Carbs
9g Protein
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Nutrition Facts
Servings: 16
Amount per serving
Calories 521
% Daily Value*
Total Fat 39g 51%
Saturated Fat 21g 107%
Cholesterol 98mg 33%
Sodium 133mg 6%
Total Carbohydrate 34g 12%
Dietary Fiber 7g 24%
Total Sugars 18g
Protein 9g
Vitamin C 0mg 1%
Calcium 83mg 6%
Iron 8mg 42%
Potassium 397mg 8%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)