1
Preheat the oven to 170°C. Melt 150 g of chocolate over steam and cool until lukewarm. Whisk the egg yolks with the icing sugar and vanilla paste. Add the melted and cooled butter and stir.
2
Whisk the egg whites with the sugar until stiff and creamy. Add the cooled chocolate to the egg yolks; sift the flour and cocoa over the mixture and mix with a hand mixer on low speed until the ingredients are combined. Finally, fold in the egg white whites in two stages with a spatula.
3
Line a baking tray (18 cm in diameter) with baking paper (bottom) and grease the sides with butter and sprinkle with flour (shake off the excess flour). Spread the mixture evenly in the tray and bake for 15 minutes with the oven door slightly ajar (stick a spatula between the doors), then close the oven door and bake for a further 40 minutes.
4
Cool the baked cake in the tin for 20 minutes, then remove from the tin and cool on a wire rack until lukewarm. While it is cooling, blend the jam smooth and heat it through.
5
Cut the lukewarm sponge cake into three equal discs, remove the crispy crust. Place the bottom part on a base and place the ring on it. Immediately spread 50 g of jam over it and cover with the other disc. Push in gently, spread with 50 g of jam and cover with the third disc, turning the top over onto the jam. Cover with the remaining jam (30 g) and leave the cake to cool.
6
Remove the ring from the cooled cake and spread the jam over the whole cake. Allow the jam to dry slightly. Using two palette knives, transfer the cake to a wire rack and prepare the icing.
7
Melt the chocolate and butter over steam, taking off a few spoonfuls that will be needed for the inscription; add the oil to the remaining chocolate and mix well. Cool the chocolate until lukewarm and pour it over the cake from the centre outwards. Using a palette knife, spread evenly, smoothly over the cake. Place the cake and the net in the fridge to set the chocolate. Once set, use two palette knives to transfer the cake back to the base and decorate with the reserved chocolate.
8
The cake should be kept at about 18°C, or if refrigerated, at room temperature for 2 hours before serving.