Separate eggs. Beat the egg whites, 4 tablespoons of water and 1 pinch of salt with the whisk of the hand mixer until stiff, adding 100 g of sugar at the end. Stir in the egg yolks one after the other. Mix flour, cocoa and baking powder, sieve over the egg mixture. Line a baking tray (approx. 30 x 38 cm) with baking paper. Add the mixture and spread evenly. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 10 minutes
Remove the baking tray from the oven, turn the sponge cake onto a tea towel sprinkled with sugar, carefully remove the baking paper. Roll up from one long side with the tea towel, let it cool down for about 1 hour
Drain the morello cherries in a sieve. Soak the gelatine in cold water. Mix quark, vanilla sugar and 4 tablespoons of sugar. Squeeze the gelatine, dissolve, stir in 3 tbsp. quark, stir into the remaining quark. Chill for about 5 minutes until the cream starts to gel. Whip the cream with the whisk of the hand mixer until stiff, put 50 g aside, fold the remaining cream into the cream
Unroll the sponge cake, spread the curd cream on top and spread evenly. Spread morello cherries on the cream, roll up the sponge cake from the long side with the help of a cloth, refrigerate for about 2 hours
Coarsely chop the chocolate coating, melt over a warm water bath, let it cool down for about 10 minutes. Spread the chocolate coating thinly on the back of a baking tray, let it set for about 15 minutes. Use a metal spatula to remove the rolls, chill. Spread the sponge roll with the cream set aside, decorate with the chocolate rolls
waiting time approx. 3 hours