Defrost raspberries at room temperature. Meanwhile, for the sponge cake, place eggs, sugar and salt in a mixing bowl and whisk until light creamy. Sift the flour, cocoa and baking powder onto the foam mixture. Carefully fold in. Line the bottom of a springform pan (26 cm Ø) with baking paper. Pour in the sponge mixture and smooth it down. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for 15-18 minutes.
Remove from the oven. Use a knife to remove the sponge cake from the edge of the mould. Let it cool down in the mould on a cake rack. Soak gelatine in cold water. Puree the raspberries. Then pass through a fine sieve. Mix raspberry puree, yoghurt, sugar, vanilla sugar and citro-back. Squeeze the gelatine, melt carefully in a small pot. While stirring, add drop by drop to the raspberry yoghurt mixture. Place in a cool place until the cream begins to gel. In the meantime, whisk the cream with the whisk of the hand mixer until stiff and fold into the gelling raspberry yoghurt mass in portions. Cut the sponge cake base twice horizontally. Place the lower cake base on a cake plate. Place a cake ring around it.
Squeeze the gelatine, melt carefully in a small pot. While stirring, add drop by drop to the raspberry yoghurt mixture. Place in a cool place until the cream begins to gel. In the meantime, whisk the cream with the whisk of the hand mixer until stiff and fold into the gelling raspberry yoghurt mass in portions. Cut the sponge cake base twice horizontally. Place the lower cake base on a cake plate. Place a cake ring around it. Spread 1/3 of the cream on the lower cake base, smooth it down. Place the second cake base on top. Spread the second third of the cream on top. Put the sponge cake lid on and spread the rest of the cream on top. Place in the fridge for about 2 hours. Carefully loosen the cake ring. Decorate the cake as you like with chocolate decoration, raspberries and lemon balm
Spread 1/3 of the cream on the lower cake base, smooth it down. Place the second cake base on top. Spread the second third of the cream on top. Put the sponge cake lid on and spread the rest of the cream on top. Place in the fridge for about 2 hours. Carefully loosen the cake ring. Decorate the cake as you like with chocolate decoration, raspberries and lemon balm