Mix 200 g butter in flakes, 100 g sugar, flour, cocoa and 1 egg to a smooth short pastry. Cover and chill for about 30 minutes. In the meantime carefully wash the berries and let them drain. Grease a fat pan of the oven (32 x 39 cm). Roll out the dough and line the pan with it. Prick several times with a fork.
Mix 150 g soft butter and 250 g sugar until creamy. Stir in 6 eggs. Add quark, cream cheese, pudding powder and cold coffee and mix carefully. Spread blackberries and 250 g blueberries evenly on top. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: not suitable/ gas: level 3) for approx. 45 minutes, let cool down. Mix the remaining blueberries and 3-4 tablespoons of sugar, allow to crystallise for 10 minutes and sprinkle over the cake