For the crumbles, mix 250 g flour, 100 g sugar, 125 g soft fat, 1 packet vanillin sugar and 1 egg with the dough shakes of the hand mixer to make crumbles. Put them in a cold place.
For the sponge mixture, whip 200 g fat, 175 g sugar and 1 sachet vanilla sugar until creamy. Stir in 4 eggs one after the other. Mix 375 g flour and baking powder and stir alternately with the milk into the dough.
Grease the oven pan (32X38 cm) and sprinkle with breadcrumbs. Pour in the dough and smooth it down. Put in a cool place for about 1 hour.
For the icing, beat 75 g fat and 100 g sugar until creamy. Add 3 eggs one after the other. Stir in the quark, sour cream and pudding powder. Spread plum puree on the sponge mixture. Add the icing and smooth it down. Spread crumbles on the icing. Bake in the preheated oven (electric: 175 °C/ gas: level 2) for 40-45 minutes until golden brown. Dust with icing sugar as desired. Whipped cream is delicious with it.