Wash, halve and stone the plums. Stir the sour cream with 2 eggs, 80 g sugar and vanillin sugar until smooth. Melt the fat. Carefully stir in 175 g flour, 70 g sugar, cinnamon and salt with the dough hooks of the hand mixer to form crumbles. Knead remaining flour with baking powder, quark, milk, oil, remaining sugar, orange peel and remaining egg to a smooth dough.
Grease the fat pan of the oven and dust with flour. Roll out the dough, cover with the plums and drizzle with a glaze. Spread crumbles on top and bake in the preheated oven (electric: 200 °C/ gas: level 3) for 30-35 minutes. Serve with whipped cream