Crumble 250 g flour, 125 g sugar, 175 g soft fat, cinnamon, vanillin sugar and a pinch of salt with the dough hooks of the hand mixer. Keep cold. Put 550 g flour and a pinch of salt in a bowl. Stir yeast with 1 tablespoon of sugar until liquid. Add 75 g sugar and liquid yeast to the flour.
Melt 75 g fat, add milk. Add lukewarm milk-fat mixture and egg to the flour and knead all ingredients to a smooth dough. Cover and leave to rise in a warm place for about 30 minutes. Wash, halve and stone the plums. Knead yeast dough again well. Grease the fat pan of the oven (38x32 cm) and roll out the dough in it. Spread the plums on the dough with the open side facing upwards. Put crumbles on top. Leave to rise for another 30 minutes in a warm place. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 30 minutes.
Spread the plums on the dough with the open side facing upwards. Put crumbles on top. Leave to rise for another 30 minutes in a warm place. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 30 minutes. Leave to cool on a rack. Cut the cake into 24 pieces and serve. Whipped cream tastes good with it