Mix lukewarm milk, 10 g sugar and yeast. Put the flour, 40 g sugar, salt and room-warm butter in a bowl. Add the milk-yeast mixture and knead with the dough hooks of the hand mixer to a smooth yeast dough.
Cover and leave to rise in a warm place for about 30 minutes. Roll out the yeast dough evenly on a greased baking tray, cover and leave to rise for a further 30 minutes. In the meantime, beat the sour cream, lemon peel, remaining sugar, vanillin sugar, poppy seed cake and eggs.
Wash, halve and stone the plums. Pull the dough up a little at the edges. Pour in a sand casting and cover with plums. Bake in the preheated oven (electric cooker: 175 °C/ gas: level 2) for approx. 30 minutes.
Let it cool down. Cut into 20 pieces and serve.