Chocolate Mousse Cake Recipe
Layers of mousse, chocolate cake and ganache.
Was this page helpful?
Help improve this recipe for others.
Send this recipe to your inbox.
We'll email it straight to you - plus weekly cooking inspiration.
Ingredients
Some product links may be affiliates. If you buy through them, you're supporting the site and Pekin may earn a commission at no extra cost to you.
Chocolate Cake Layer
Dark Chocolate Mousse
Chocolate Ganache (Top Glaze)
Assembly & Finish
Method
Chocolate Cake Layer
- 1
Prepare and mix dry ingredients
Preheat oven to 350°F (175°C). Grease an 8-inch round springform pan (or line with parchment) and set aside. In a medium bowl whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt until evenly combined.
- 2
Combine wet ingredients
In a separate bowl whisk the egg, buttermilk, vegetable oil and vanilla until smooth.
- 3
Mix batter and bake
Add the wet mixture to the dry ingredients and stir until just combined. Stir in the hot water slowly until batter is smooth and slightly thin (this keeps the cake moist). Pour batter into prepared pan and bake for 18–22 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Allow cake to cool in the pan on a wire rack for 10 minutes, then remove the outer ring (if using springform) and cool completely on the rack. Once cooled, trim the top if necessary to make a level layer and return to the springform base or place on a cake board; chill briefly (10–15 minutes) so it’s firm for mousse assembly.
Dark Chocolate Mousse
- 4
Melt chocolate
Place chopped bittersweet chocolate in a heatproof bowl. Heat 1/2 cup of the heavy cream just until simmering (do not boil) and pour over the chocolate. Let sit 1 minute, then whisk until smooth and glossy. Add the diced cold butter and whisk until incorporated. Set aside to cool slightly.
- 5
Tempered egg yolks
In a small bowl whisk the egg yolks with the sugar and salt until slightly pale. Slowly pour 2–3 tablespoons of the warm chocolate mixture into the yolks while whisking constantly to temper them. Then pour the yolk mixture back into the main chocolate bowl and whisk until fully combined and smooth. Allow mixture to cool to room temperature (so it won’t deflate whipped cream).
- 6
Whip cream and fold
Whip the remaining 1.5 cups heavy cream to soft peaks (begin whipping cold cream with a chilled bowl and beaters if possible). Reserve about 1/4 cup of whipped cream to pipe or smooth the edges if desired. Fold one-third of the whipped cream into the chocolate mixture gently to loosen it, then fold in the remaining whipped cream in two additions until homogeneous and airy, taking care not to overmix.
- 7
Assemble mousse layer
If using the cooled cake in a springform pan, place a removable acetate ring or baking parchment collar inside the pan around the cake edge. Spoon or pipe the mousse over the cooled cake, spreading gently to an even layer about 1 to 1-1/2 inches thick. Smooth the top with an offset spatula. Refrigerate for at least 2 hours (ideally 4 hours) to set, or freeze for 30–45 minutes to speed up.
Chocolate Ganache (Top Glaze)
- 8
Make ganache
Place chopped semisweet chocolate in a bowl. Heat 1/2 cup heavy cream until just simmering and pour over chocolate. Let sit 30–60 seconds then whisk until smooth. Whisk in the teaspoon of butter for extra shine if using. Cool ganache until it’s thickened but still pourable (about 5–10 minutes).
- 9
Glaze the cake
Remove chilled mousse-topped cake from refrigerator. If using a springform, release sides and remove ring only if cake is fully set and can be transferred; otherwise leave ring and glaze in pan. Place cake on a wire rack set over a baking sheet to catch drips. Pour ganache into the center and gently coax it toward the edges with a spatula so it flows over the sides to create an even glossy coat. Use an offset spatula to tidy edges if needed. Return cake to refrigerator for 20–30 minutes to let ganache set.
Assembly & Finish
- 10
Finish and serve
Once ganache has set, transfer cake to a serving plate if it was glazed on a rack. Dust the top lightly with cocoa powder or scatter chocolate shavings. Garnish with fresh berries or mint if desired. Allow cake to sit at room temperature 10–15 minutes before slicing for cleaner slices. Use a hot, dry knife wiped between slices to cut neat pieces.