Preheat your oven to 180°C (350°F). Grease and line an 8-inch round cake tin with parchment paper.

In a mixing bowl, whisk together the eggs, light brown sugar, granulated sugar, and vanilla until the mixture is thick and pale.

Sift the flour, cocoa powder, baking powder, espresso powder, and salt into the egg mixture. Gently fold in the melted dark chocolate until fully combined.

Pour the batter into the prepared cake tin and bake for about 20-25 minutes, or until a toothpick comes out clean. Let it cool completely before removing from the tin.

In a small bowl, combine the powdered gelatine and lemon juice. Allow it to sit until it blooms (about 5 minutes).

In a saucepan, gently heat 100 g of granulated sugar with the fresh raspberries over low heat until they start to break down. Remove from heat and stir in the bloomed gelatine until dissolved. Allow to cool slightly.

In a separate bowl, whip the cold double cream until soft peaks form. Carefully fold the raspberry mixture into the whipped cream until no streaks remain.

Once the chocolate sponge is cool, slice it in half horizontally. Place one layer in a springform pan, pour half of the raspberry mousse over it, then place the other layer on top.

Spread the remaining mousse over the top and chill in the fridge for at least 4 hours, or overnight if possible.

Carefully release the cake from the springform pan and place it on a serving plate.

Garnish the top with fresh raspberries and chocolate shavings for an elegant finish.