Chef's Tip
When making the mousse, fold the whipped cream into the chocolate mixture very gently to maintain maximum airiness. For the cleanest slices, use a hot, dry knife (run under hot water and wipe dry) to cut the cake, cleaning and reheating the knife between each slice.
Instructions
- Preheat oven to 350°F. Grease a 9-inch springform pan and line the bottom with parchment paper.
- Make the cake: In a large bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt.
- In another bowl, whisk together eggs, buttermilk, oil, and vanilla.
- Add wet ingredients to dry ingredients and mix until just combined. Stir in hot coffee (batter will be thin).
- Pour batter into prepared pan and bake for 30-35 minutes, until a toothpick inserted in center comes out clean. Let cool completely on a wire rack.
- Once cool, remove from pan and slice horizontally to create two equal layers. Clean the springform pan and reassemble with the bottom cake layer inside.
- Make the chocolate mousse: Melt 8 oz of dark chocolate with butter in a heatproof bowl set over simmering water. Let cool slightly.
- Beat egg yolks with 2 tbsp sugar until pale and thick. Fold into the cooled chocolate mixture.
- In a separate bowl, whip heavy cream until soft peaks form.
- In another bowl, beat egg whites until foamy, then gradually add remaining 2 tbsp sugar and beat until stiff peaks form.
- Gently fold whipped egg whites into the chocolate mixture, then fold in the whipped cream until just combined.
- Pour half the mousse over the bottom cake layer in the springform pan. Place the second cake layer on top, then cover with remaining mousse. Smooth the top and refrigerate for at least 4 hours or overnight.
- Make the ganache: Heat 1/2 cup heavy cream until hot but not boiling. Pour over 4 oz chopped chocolate and let sit for 1 minute, then stir until smooth.
- Pour ganache over the chilled cake, tilting to spread evenly. Return to refrigerator for 30 minutes to set.
- Just before serving, whip 1 cup heavy cream with powdered sugar and vanilla until stiff peaks form.
- Release cake from springform pan. Serve slices with whipped cream and chocolate shavings.
Plating
Slice the cake and place each portion on a dessert plate, positioning it slightly off-center. Add a generous dollop of whipped cream beside the cake. Dust the plate and cake with a light sprinkle of chocolate shavings. For an elegant presentation, drizzle a thin line of chocolate sauce on the plate in a curved pattern and add a small mint leaf or edible flower as a finishing touch.
Storage & Reheating
The assembled cake can be refrigerated for up to 3 days, covered loosely with plastic wrap once the ganache has set. For best texture and flavor, bring to room temperature for about 20 minutes before serving. The cake can also be frozen without the ganache for up to 1 month; thaw overnight in the refrigerator and add the ganache before serving.
About This Recipe
This Belgian Chocolate Mousse Cake draws inspiration from the luxurious dessert served at The Student Prince restaurant. The home version captures the same decadent combination of chocolate cake and silky mousse that makes the original so popular. Using premium Belgian chocolate ensures a rich, complex chocolate flavor that elevates this dessert from everyday chocolate cake to something truly special.