For the yeast dough, heat milk and dissolve yeast in it. Put flour, 60 g sugar, salt, egg yolk and fat in a bowl. Add yeast milk and knead to a smooth dough. Cover and leave to rise in a warm place for about 30 minutes.
In the meantime, wash the plums, cut them in half, remove the seeds and cut them into slices. Knead the yeast dough again and press it into a greased tart tin (26 cm Ø). Spread the plums on top.
Mix eggs, sour cream and remaining sugar. Pour over the plums and bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for approx. 30 minutes. Let them cool down on a cake rack.
Dust with icing sugar and cinnamon. Makes 8 pieces.