Chocolate Mouse Cake Recipe

Prepare and preheat

Preheat the oven to 350°F (175°C). Grease an 8-inch springform pan and line the bottom with parchment paper. Lightly grease the parchment.

Dry ingredients

In a medium bowl, whisk together 0.75 cups all-purpose flour, 0.25 cups cocoa powder, 1 tsp baking powder and 0.25 tsp salt until evenly combined.

Wet ingredients

In a separate large bowl, whisk together 2 large eggs and 0.75 cups granulated sugar until pale and slightly thickened (about 1–2 minutes by hand or 30–45 seconds with a mixer). Add 0.5 cups whole milk, 3 tbs vegetable oil and 1 tsp vanilla extract and whisk until smooth.

Combine and bake

Add the dry ingredients to the wet ingredients and fold gently until just combined—do not overmix. Pour the batter into the prepared 8-inch pan and smooth the top. Bake for 18–22 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Remove from the oven and let cool in the pan on a wire rack for 10 minutes, then release the springform and cool completely on the rack (about 30–40 minutes). Once cool, if the top domed, level it with a serrated knife to create an even surface for mousse.

Melt chocolate

Place 8 oz chopped dark chocolate in a heatproof bowl. In a small saucepan, heat 0.5 cups of the heavy cream (reserved from the 2 cups) just until it barely simmers. Pour the hot cream over the chopped chocolate and let sit 1 minute, then stir until smooth. Stir in 1 tbs unsalted butter, 1 tsp vanilla and 0.125 tsp fine salt. Set this chocolate mixture aside to cool to room temperature.

Whip cream

Place a chilled mixing bowl and whisk attachment in the freezer for 5 minutes (optional) to help whipping. Pour the remaining 1.5 cups heavy cream and 2 tbs granulated sugar into the chilled bowl. Whip to soft-to-medium peaks—when the whisk lifts, peaks should hold shape but the tips will slightly fold. Do not overbeat to stiff peaks.

Fold mousse

When the melted chocolate has cooled but is still pourable (similar temperature to the whipped cream), spoon about one-quarter of the whipped cream into the chocolate and stir quickly to lighten the chocolate. Then gently fold in the remaining whipped cream in two additions using a spatula until homogeneous with light, airy texture. Do not overfold; keep as much air as possible.

Chill mousse layer

Place the cooled cake base into the springform pan again (or use a cake ring on a serving plate). Spoon the mousse over the cake layer, smoothing the top with an offset spatula to an even layer. Refrigerate for at least 2 hours, preferably 3–4 hours, until mousse is set and sliceable.

Make ganache

Place 4 oz chopped dark chocolate in a bowl. Heat 0.5 cups heavy cream in a small saucepan until it just begins to simmer, then pour over the chocolate. Let sit 1 minute, then stir until smooth. Stir in 1 tbs unsalted butter for shine. Cool 8–10 minutes until slightly thickened but still pourable.

Glaze cake

Remove the chilled mousse cake from the refrigerator and release it from the springform pan or set the cake on a wire rack over a tray. Pour the ganache over the center of the mousse and gently nudge it to flow to the edges; use an offset spatula to smooth and catch drips. Return to the fridge for 15–30 minutes to set the ganache.

Once the mousse (and ganache, if using) is fully set, carefully remove the cake from the ring or transfer it to a serving plate. Lightly dust the top with 1 tsp cocoa powder using a fine sieve and add 2 tbs chocolate shavings or curls if desired. Let the cake sit 10 minutes at room temperature before slicing for clean cuts. Slice with a hot, clean knife (wipe between cuts) and serve chilled or at cool room temperature.