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Best Chocolate Mousse Cake Recipe with Silky Ganache

Best Chocolate Mousse Cake

A rich chocolate brownie-style base is topped with airy semisweet chocolate mousse and an optional smooth ganache topping. Chill overnight for the cleanest slices and fullest chocolate flavor.
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Prep Time 45 minutes
Cook Time 25 minutes
Total Time 7 minutes
Servings: 10 servings
Ingredients Method Notes

Ingredients
  

Chocolate Cake or Brownie Base
  • 6 tablespoons (85 g) Unsalted butter
  • 4 ounces (113 g) Bittersweet or semisweet chocolate, chopped
  • 3/4 cup (150 g) Granulated sugar
  • 1 large Large egg
  • 1 teaspoon Vanilla extract
  • 1/2 cup (60 g) All-purpose flour
  • 1/3 cup (28-30 g) Unsweetened cocoa powder
  • 1/4 teaspoon Fine salt
Chocolate Mousse
  • 8 ounces (225 g) Semisweet or bittersweet chocolate, finely chopped
  • 1 1/2 cups (360 ml) Cold heavy cream
  • 1/4 cup (30 g) Confectioners' sugar
  • 1 teaspoon Vanilla extract
  • 1 pinch Fine salt
Optional Ganache
  • 4 ounces (113 g) Semisweet or bittersweet chocolate, chopped
  • 1/2 cup (120 ml) Heavy cream
  • 1 tablespoon, optional Unsalted butter
Optional Decoration
  • As needed Chocolate curls or shavings
  • As needed Unsweetened cocoa powder
  • As needed Whipped cream
  • As needed Fresh raspberries or strawberries

Method
 

Step-by-Step
  1. Heat the oven to 350°F (175°C). Grease a 9-inch springform pan and line the bottom with parchment paper.
  2. Melt the butter and 4 ounces of chopped chocolate together over barely simmering water or in short microwave intervals. Stir until smooth and let the mixture cool slightly.
  3. Whisk the sugar, egg, and vanilla into the melted chocolate mixture. Sift in the flour, cocoa powder, and salt, then stir only until combined.
  4. Spread the batter evenly in the prepared pan. Bake for 20–25 minutes, until the center is set and a toothpick comes out with a few moist crumbs. Cool completely in the pan.
  5. Melt the 8 ounces of mousse chocolate and let it cool until warm but not hot. Whip the cold heavy cream with the confectioners' sugar, vanilla, and salt to medium or medium-stiff peaks.
  6. Stir approximately one-third of the whipped cream into the melted chocolate to lighten it. Gently fold in the remaining whipped cream in two additions until no white streaks remain.
  7. Spread the mousse over the completely cooled cake base, smooth the top, and refrigerate for at least 6 hours, preferably overnight.
  8. For the ganache, heat the cream until steaming but not boiling. Pour it over the chopped chocolate, let it stand for 2–3 minutes, and stir until smooth. Blend in the butter if using.
  9. Cool the ganache until slightly thickened, then spread or pour it over the chilled mousse cake. Refrigerate again for 30–60 minutes before serving.
  10. Run a warm, dry knife around the edge of the pan before releasing the springform ring. Cut with a hot, dry knife for neat slices and decorate as desired.

Notes

Use good-quality chocolate in the 55–70% cacao range. Chill overnight when possible for firmer mousse and easier unmolding. For clean slices, dip a thin knife in hot water, wipe it dry, and reheat and wipe it between cuts.