** Day 1: Bake the Genoise Cake Layer

Preheat the oven to 180°C (350°F). Grease and lightly flour a 20cm round tin.

Melt the butter in a pan and set aside to cool.

Beat the eggs and caster sugar with an electric mixer for about 12 minutes, until the mixture becomes pale and falls in thick ribbons.

Sift the flour and cocoa over the egg mixture, and gently fold them in until combined.

Drizzle in the melted butter and fold it in carefully. Do not over-mix.

Pour the batter into the prepared tin and bake for 30 minutes, or until a skewer inserted comes out clean.

Let the cake cool for 10 minutes in the tin, then transfer to a wire rack to cool completely.

In a small pan, heat the raspberry liqueur and sugar until dissolved. Brush this mixture over the cake layers to moisten them.

Slice the cake into two layers and wrap in greaseproof paper and foil. Store in the freezer or an airtight container until ready to use.

** Day 1: Prepare the Hidden Raspberry Layer

Line an 18cm tin with cling film, allowing enough to hang over the sides.

Puree the raspberries in a food processor, then push the puree through a fine sieve to remove the seeds.

Soak the gelatin sheets in cold water for 5 minutes (optional for a firmer layer).

Warm the raspberry puree gently in a pan to about 35°C, then stir in the gelatin until dissolved.

Add the sugar and liqueur (if using), and stir until dissolved.

Pour the mixture into the lined tin and freeze for 1 hour, or until firm. Cover with cling film and leave in the freezer overnight.

** Day 2: Make the White Chocolate Mousse

Set a bowl over a pan of simmering water and add the finely chopped white chocolate. Stir occasionally until half-melted, then remove from heat to finish melting.

Soak the gelatin in cold water for 5 minutes (optional).

Heat the milk until just boiling, then remove from heat. Squeeze the gelatin and add it to the milk, stirring to dissolve (if using gelatin).

In a separate bowl, mix the egg yolks and liquid glucose with 3 tablespoons of warm water until combined.

Whip the cream and icing sugar in another bowl until soft peaks form.

Pour the warm milk into the melted white chocolate and whisk until smooth.

Stir in the egg yolk mixture, then gently fold in the whipped cream until fully incorporated.

** Day 2: Assemble the Cake

Line the same cake tin you used to bake the cake with cling film.

Place one layer of the cake at the bottom of the tin.

Pour the white chocolate mousse over the cake layer.

Remove the raspberry layer from the freezer and gently press it into the mousse, ensuring it is centered and halfway submerged.

Freeze the cake overnight for best results.

** Day 3: Serve the Cake

To remove the cake from the tin, warm the sides using a hair dryer or kitchen blowtorch.

Slice the cake with a warm knife for clean cuts, wiping the knife between slices.

Serve slightly frozen or fully thawed, depending on your preference.