For the dough mix flour and cocoa. Knead with 450 g butter in pieces, 270 g sugar, salt and 1 packet vanilla sugar with the dough hooks of the hand mixer. Remove approx. 1/3 of the dough for the crumbles, cover and chill. Spread the remaining dough evenly in a greased fat pan (36 x 41 cm) and press firmly.
Wash, clean and stone the cherries. Separate eggs. Beat the egg whites in portions with the whisk of the hand mixer until stiff. Cream 100 g butter with 300 g sugar. Add egg yolks, pudding powder, quark, 1 sachet vanilla sugar and sour cream and stir well. Fold in the egg white in portions. Spread about half of the cheese mixture on the base and smooth it down. Spread the cherries on top.
Pour the rest of the cheese mixture over it. If necessary, work the remaining dough into crumbles with 1 tbsp. flour by hand. Spread the crumbles on the cheese mixture and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) below the middle shelf for approx. 1 hour. Remove the cake from the oven and let it cool down on a cake rack. Dust the cake with icing sugar, cut into pieces and arrange on a plate. Whipped cream tastes good with it.