For layer 1, knead flour, cocoa, baking powder, sugar, vanilla sugar, salt, egg, water and butter with the dough hook of the mixer to form a smooth dough and roll out on a greased baking sheet (approx. 35 x 40 cm).
For layer 2, wash the blueberries and let them drain very well on paper towels. Spread on the dark dough. (Or use drained mandarins or raisins instead of the blueberries).
For layer 3, mix the quark, sour cream, butter, sugar, lemon and eggs to a smooth cream, spread over the fruit.
For layer 4, process flour, pudding powder, sugar, oil and water with the whisk of the hand mixer into very fine sprinkles, sprinkle over the quark layer.
Bake at 180 degrees top / bottom heat for approx. 35 - 45 minutes.