Chocolate Mousse Cake
Ingredients
**For the biscuit crust**
- 180 g 6.3 oz digestive biscuits
- 75 g 2.6 oz unsalted butter, melted
**For the chocolate mousse**
- 250 g 8.8 oz milk chocolate, finely chopped
- 100 g 3.5 oz dark chocolate, around 60–70% cocoa, finely chopped
- 500 ml about 2 cups heavy whipping cream, divided into 200 ml and 300 ml
**For the chocolate drizzle**
- 60 g 2.1 oz dark chocolate
- 60 ml ¼ cup heavy cream
**To serve**
- Whipped cream optional
- Fresh mint leaves optional
Method
- Line a 20 cm (8-inch) square cake tin with parchment paper, leaving enough overhang to lift the cake out later.
- Crush the digestive biscuits into fine crumbs using a food processor or rolling pin. Mix with the melted butter until the crumbs resemble damp sand.
- Press the biscuit mixture firmly and evenly into the bottom of the prepared tin. Refrigerate while preparing the chocolate mousse.
- Place the chopped milk chocolate and dark chocolate in a heatproof bowl.
- Heat 200 ml of the cream in a small saucepan until steaming but not boiling. Pour over the chopped chocolate and leave for 2 minutes. Stir gently until completely melted and smooth.
- Allow the chocolate mixture to cool to lukewarm, stirring occasionally. It should remain fluid but no longer feel hot.
- Whip the remaining 300 ml of cold cream to soft peaks using an electric mixer.
- Fold one-third of the whipped cream into the cooled chocolate mixture to loosen it. Gently fold in the remaining whipped cream in two additions until evenly combined.
- Spoon the chocolate mousse over the chilled biscuit crust and smooth the surface with a spatula.
- Cover and refrigerate for at least 6 hours, preferably overnight, until the mousse is firm enough to slice.
- To make the chocolate drizzle, heat 60 ml of cream until steaming. Pour over 60 g of chopped dark chocolate, leave for 1 minute, then stir until smooth. Allow to cool until slightly thickened but still pourable.
- Lift the chilled cake carefully from the tin and cut into eight rectangular slices using a sharp knife, wiping the blade clean between cuts.
- Place each slice on a dessert plate and drizzle with the chocolate sauce. Serve with a little whipped cream and a fresh mint leaf, if desired.
Notes
Chocolate: Use good-quality chocolate, like Valor.The combination of milk and dark chocolate gives the mousse a balanced flavor and a texture firm enough to slice once chilled.
Cream: Use heavy whipping cream with approximately 35% fat. Lower-fat cream may not whip or set properly.
Temperature: The melted chocolate must cool to lukewarm before adding the whipped cream. If it is too hot, the mousse may lose its airy texture.
Make ahead: Prepare the cake the day before serving. Keep the chocolate drizzle separate until you're ready to plate the dessert.
Serving: For clean slices, use a sharp knife warmed briefly in hot water and wiped dry.
Storage: Keep covered in the refrigerator at 4°C (40°F) or below and enjoy within 3 days.