Ingredients

• 70g/2â…“oz unsalted butter
• softened
• 70g/2â…“oz icing sugar
• 2 free-range egg whites
• 40g/1½oz plain flour
• sifted
• 40g/1½oz cocoa powder
• sifted
• 2 free-range egg whites
• 10g/â…“oz caster sugar
• 60g/2¼oz ground almonds
• 60g/2¼oz icing sugar
• 2 free-range eggs
• 20g/¾oz plain flour
• sifted
• 20g/¾oz unsalted butter
• melted
• 150g/5½oz plain chocolate (36% cocoa solids)
• chopped
• knob of butter
• 2 free-range eggs
• separated
• 1 tbsp brandy (optional)
• 100ml/3½fl oz double cream
• 300g/10½oz white chocolate
• chopped
• 100ml/3½fl oz double cream
• 1 free-range egg white
• 100g/3½oz fresh berries (raspberries and blueberries work well)
• icing sugar
• for dusting

Directions

• Grease and line a 33x23cm/13x9in Swiss roll tin with baking parchment. Cut a sheet of baking silicone to fit the base of the Swiss roll tin. Line a baking tray with baking parchment and lay the silicone sheet on top.
• For the decorative paste
• cream the butter and icing sugar together until light and fluffy. Gradually add the egg whites
• beating continuously. Fold in the flour and cocoa powder until combined.
• Spread the paste thinly and evenly over the silicon mat using a palette knife. Drag a pastry comb diagonally through the paste to form a pinstripe pattern
• scraping off the excess mixture after each drag. Place the paste in the freezer for 15 minutes.
• For the joconde sponge
• preheat the oven to 220C/200C(fan)/Gas 7.
• Whisk the egg whites in a bowl until stiff peaks form when the whisk is removed. Add the caster sugar
• one teaspoon at a time
• whisking between each addition to make a glossy meringue. Cover with cling film and set aside.
• Tip the ground almonds and icing sugar into the bowl of a freestanding mixer and add the whole eggs. Whisk together for 3-5 minutes
• or until doubled in volume. Fold in the flour
• and then gently fold in the meringue in three separate batches. Pour the melted butter down the side of the bowl and fold in
• until incorporated.
• Remove the silicone sheet with the decorative paste from the freezer and place into the base of the lined Swiss roll tin.
• Tip the joconde sponge mixture over the pinstripe paste and level the surface with a palette knife. Bake for 5-7 minutes
• or until pale
• golden-brown and springy to touch.
• Place a sheet of baking parchment over a cooling rack and turn the cake out onto it. Peel off the baking parchment and silicon sheet from the base of the cake and leave to cool completely.
• Line the sides of 6 x 6.5cm/2½in chefs’ rings with baking parchment. Cut a rectangular template measuring 17x5cm/6½x2in
• from a piece of parchment paper.
• When the sponge is cooled
• trim the edges and cut out six rectangles of sponge using the template. Wrap the cake strips inside the cake rings
• stripey side facing out. Once wrapped inside the rings
• gently push and press the ends to meet together to make a seamless cake. You want the joconde to fit very tightly pressed up to the sides of the cake rings.
• Using a small 4cm/1½in round cutter
• cut out small circles from the cake trimmings and push them into the base of the cake rings.
• For the dark chocolate mousse
• place the chocolate in a bowl set over a pan of simmering water (ensure the bottom of the bowl does not touch the water). Melt slowly and do not allow the chocolate become too hot. 

• Stir in the butter and mix until combined. Add the egg yolks and brandy and set aside to cool a little.
• In a bowl
• whisk the egg whites until stiff peaks form when the whisk is removed. Fold into the chocolate mixture until completely incorporated.
• Whip the cream until soft peaks form when the whisk is removed. Fold into the chocolate and egg white mixture.
• Spoon the mousse into a disposable piping bag and pipe into the cake lined rings
• until the mousse comes three-quarters of the way up the sponge. Chill them in the freezer while you make the white chocolate mousse.
• For the white chocolate mousse
• place the chocolate in a bowl set over a pan of simmering water (do not allow the bottom of the bowl to touch the water). Melt very gently
• but do not allow the chocolate to become too hot. 

• In a bowl
• whisk the egg whites until stiff peaks form when the whisk is removed. Fold into the white chocolate mixture.
• In a bowl
• whip the cream until soft peaks form when the whisk is removed and fold into the white chocolate mixture.
• Spoon the white chocolate mousse into a disposable piping bag and pipe on top of the chocolate mousse until it reaches the top of the cake rings. Chill in the fridge until set.
• Once set
• turn out of the cake rings and place on serving plates. Top with the raspberries and blueberries and dust with icing sugar.