Mix 300 g flour, baking powder, 60 g sugar and salt. Add milk, oil, eggs and quark. Mix the ingredients with the dough hooks of the hand mixer to a smooth dough
Roll out the dough on a floured work surface to the size of the fat pan, grease the fat pan of the oven (approx. 32 x 39 cm) and place the dough inside with the help of a dough roller. Spread the jam evenly on the dough. Wash plums, grate dry, cut in half, remove stones and cut plum halves in half again. Spread plums evenly on the dough
Mix 120 g flour, 50 g sugar, vanillin sugar in a bowl. Add 100 g butter in small pieces and 1 tablespoon of water, knead into crumbles with your hands. Coarsely crumble the Amarettini and mix into the crumbles. Spread the crumbles on the plums, sprinkle with 50 g small flakes of butter and about 2 tablespoons of sugar. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 45 minutes
Serve the cake hot or cold as desired. Whipped cream tastes good with it