1. Separate the eggs. Beat the egg whites with 2 tbsp warm water. Beat the egg yolks, sugar and vanilla sugar until creamy.
2. Add the stiffly beaten egg whites to the egg yolks. Then mix the flour, baking powder and cornstarch, sift onto the egg mixture and carefully fold in.
3. Spread the dough on a baking sheet lined with baking paper, bake at 200°C for approx. 15 minutes and turn out onto a sugared tea towel while still hot, roll up and leave to cool.
4. Now soak the gelatine for the filling. Mix the quark, sugar, vanilla sugar, lemon juice and zest. Then squeeze out the gelatine, dissolve it and stir it drop by drop into the quark mixture, leave to cool. Whip the cream. Then, as soon as the lemon mixture begins to set, fold in the cream.
5. Unroll the sponge cake, spread with cream, roll up again and leave to cool for approx. 3 hours. Dust the roll with icing sugar
