Sift the flour onto a work surface and form a volcano. Place all the other ingredients in the centre and mix together, gradually incorporating the flour. Work everything into a smooth dough as quickly as possible.

Shape the dough into a ball, wrap in cling film and refrigerate for one hour.

Roll out the dough into the desired shape and place in a greased tart tin. Prick the dough several times with a fork and refrigerate again until ready to use.

Mix the quark, sugar, vanilla sugar, egg yolks and cornflour.

Whip the cream until firm peaks form and fold into the quark mixture. Beat the egg whites until stiff and fold them in.

Spread the mixture evenly over the pastry. Preheat the oven to 185°C (top and bottom heat). Bake the cake for 40–50 minutes.

Place a wire rack upside down over the tin while the cake is still warm and flip over so that the bottom of the cake is facing up.

Leave the cake to cool with the top facing downwards — this will keep it firm.

Turn the cake over again and transfer it to a serving plate. Dust with icing sugar before serving.