Knead butter, flour, 100g sugar, cocoa, 1 egg yolk and 5 tablespoons cold water and salt to form a dough. Cover and chill for 30 minutes.
Roll out the dough up to 75g and press firmly in a springform pan. Prick the base several times with a fork and chill.
Cut the peaches into small pieces.
Mix the quark, mascarpone, 250g sugar, lemon juice, 5 eggs, 1 egg white, custard powder and semolina with a whisk until creamy. Add the peach pieces and pour the quark mixture into the springform pan and smooth it out.
Bake in a preheated oven (fan oven 150 °) for about 1 hour. Halfway through the baking time, roll out the remaining dough and cut out with cookie molds. Spread on top of the cake and continue baking.