Wash the plums and drain well. Cut the plums in half, remove stone and cut the halves into thick slices. Mix quark, 6 tablespoons of milk, oil, sugar, vanillin sugar and salt.
Mix flour and baking powder and stir half of it into the quark mixture by the spoonful. Knead in the rest of the flour. Form the dough into a thick roll on a well floured work surface and cut into 12 pieces.
Press each piece flat to form a round disc (9-10 cm Ø). Place on two baking trays lined with baking paper. Pour 300 ml milk into a mixing bowl, add cream powder and mix with the whisks of the hand mixer on the lowest setting for about 1 minute.
Then whip on highest level for about 1 minute. Spread the pudding cream as a blob on each piece of dough and generously cover with the plum wedges. Sprinkle the plums with sugar and coat the edges of the dough with cream.
Bake the trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 15-20 minutes. Let them cool down.