Beat butter with sugar until frothy, add eggs one after the other. Mix in the flour and baking powder, as well as the milk. Spread the dough on a baking sheet lined with baking paper. Mix the quark with the egg and sugar and spread on the dough. Wash and chop the fruit and spread it on the dough, e.g. cut the plums in half and spread them on the quark like scales, cut the apples into wedges. Also tastes very tasty with currants, blackberries or cherries.
Mix all the ingredients for the crumble and spread over the fruit. Bake in the preheated oven at 180 ° C for about 1 hour.