Warm the milk lukewarm. Put 250 g flour, 35 g sugar and salt in a bowl. Press a depression in the middle. Mix the yeast and 5 tablespoons of milk and place in the flour bowl. Mix with flour from the edge and dust with a little flour.
Cover and leave to rise in a warm place for about 15 minutes. Melt 125 g butter and let it cool down a little. Mix 150 g flour, vanillin sugar and 75 g sugar. Stir in liquid butter with the dough hooks of the hand mixer and knead into crumbles. Put the crumbles in a cool place. Add 40 g butter, egg and remaining milk to the yeast dough and knead into a smooth dough using the dough hooks of the hand mixer. Cover the dough again and let it rise for about 30 minutes. Briefly knead the dough on a floured work surface, then roll out to a flat cake (3-4 mm thin). Place the flat cakes on a baking tray lined with baking paper and spread with jam, leaving about 1/2 cm space around the edges. Spread the crumbles on the jam.
Cover the dough again and let it rise for about 30 minutes. Briefly knead the dough on a floured work surface, then roll out to a flat cake (3-4 mm thin). Place the flat cakes on a baking tray lined with baking paper and spread with jam, leaving about 1/2 cm space around the edges. Spread the crumbles on the jam. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 20-25 minutes. Remove the crumble cake from the oven and let it cool down on a cake rack. Serve lukewarm or cold
1 1/2 hours waiting time