Serves 8-10 – Overnight refrigeration – Prep: 1h 15min + overnight setting

Put the frozen berries, 2 tablespoons of water and 100g sugar in a saucepan and bring to the boil. Cook uncovered on a high heat for about 15 minutes until it forms a compote, stirring regularly. Crush the thicker fruit with a potato masher so you get a compote without any big bits. Pour into a bowl and set aside to cool for 1 hour.

Finely chop both chocolates.

Pour 150ml of cream into a saucepan and bring to a simmer. Take the cream off the heat and stir in the chocolate until fully melted. Pour into a large bowl and set aside to cool for 30 minutes.

Meanwhile, prepare the base: put the ring of a 23cm Springform onto a nice serving plate (without the bottom). Cut the bottom off most of the sponge finger biscuits so that they are slightly higher the tin. Place them upright all around the sides of the tin. Arrange a layer of sponge finger biscuits on the bottom, crumbling up some of the biscuit trimmings to fill any holes.

Cover the base with the berry compote.

After 30 minutes, whip the egg whites with a pinch of salt until stiff. Put into the bowl with the melted chocolate, but don’t mix yet.

In the bowl used for the egg whites, whip the remaining 150ml cream with the sugar until stiff.

Add the whipped cream to the melted chocolate and the stiff egg whites in the bowl and gently fold through until fully combined.

Pour the chocolate mousse over the base of the springform and refrigerate overnight.

The next day, take the cake out of the fridge, remove from its tin and transfer onto a serving plate.

Dust the cake surface with cocoa powder. Decorate the outer circle of the cake with raspberries and place a few raspberries in the middle.

Serve immediately or refrigerate until needed.