Put 300 g flour, 75 g sugar, salt, 1 packet vanilla sugar, 1 egg and 75 g butter in a mixing bowl. Heat milk lukewarm, crumble yeast into it and dissolve it while stirring. Add yeast milk to the flour mixture and knead to a smooth dough using the dough hooks of the hand mixer. Cover the dough and let it rise in a warm place for about 40 minutes.
In the meantime, wash the plums, drain them, cut them in half and stone them. Put 250 g flour, 175 g sugar, 1 egg, 1 packet vanillin sugar, cinnamon and 125 g butter in a bowl and work it into crumbles
Knead the yeast dough again with floured hands on a floured work surface. Form into a roll (approx. 25 cm long), cut into 8 pieces of the same size, shape into flat cakes (approx. 10 cm Ø) with floured hands. Distribute at a distance on two baking trays lined with baking paper. Cover and leave to rise in a warm place for about 20 minutes
Cover the dough pieces of the first tray evenly with about half of the plums. Whisk the egg yolk and 1 tbsp. water, brush the edges of the flat bread with it. Spread approx. half of the crumbles evenly on the plums and bake in the preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 20 minutes. Remove from the oven and let cool on a cake rack. Process remaining flat cakes, plums and crumbles in the same way. Arrange the flat cakes dusted with icing sugar
Preparation time approx. 1 3/4 hours. waiting time approx. 30 minutes