Separate the eggs for the sponge cake. Beat the egg white and 4 tablespoons of cold water until very stiff. Add sugar, vanilla sugar and salt. Stir in the egg yolk. Sieve the cocoa, flour, starch and baking powder onto the egg mixture and fold in. Line the bottom of a springform pan (26 cm Ø) with baking paper. Fill in the dough and smooth it down.
Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 15 minutes. Remove the sponge cake base from the tin, remove the baking paper and let the base cool down. Wash, clean and chop the strawberries, except for 6 pieces for decoration. Stir starch and 3-4 tablespoons of juice until smooth. Boil up the rest of the juice and 1 tablespoon of sugar. Stir in the starch, fold in the strawberries and leave to cool. Whip the cream, vanilla sugar and remaining sugar until stiff, pour in the cream firming agent. Cut the sponge cake horizontally twice. Sprinkle individual layers with liqueur. Place the edge of a springform pan around the lowest cake base, spread strawberries on the cake base. Spread 1/4 of the cream on top. Cover with a second cake base. Spread this with warmed jam.
Cut the sponge cake horizontally twice. Sprinkle individual layers with liqueur. Place the edge of a springform pan around the lowest cake base, spread strawberries on the cake base. Spread 1/4 of the cream on top. Cover with a second cake base. Spread this with warmed jam. Spread another quarter of the cream on top, cover with the last cake layer and press down gently. Spread the cream all around the cake, except for some decoration. Peel small curls from the chocolate with a peeler and decorate the edge of the cake with them. Pour the rest of the cream into a piping bag with a star-shaped spout and squirt it onto the cake as tuffs. Decorate the tuffs with strawberry halves and possibly pour some warmed jam over them. Decorate the cake with balm leaves as desired. Makes 16 pieces
Spread another quarter of the cream on top, cover with the last cake layer and press down gently. Spread the cream all around the cake, except for some decoration. Peel small curls from the chocolate with a peeler and decorate the edge of the cake with them. Pour the rest of the cream into a piping bag with a star-shaped spout and squirt it onto the cake as tuffs. Decorate the tuffs with strawberry halves and possibly pour some warmed jam over them. Decorate the cake with balm leaves as desired. Makes 16 pieces