Heat the milk lukewarm, add the butter and let it melt. Dissolve sugar and yeast in it. Mix with a little flour and cover and let rise for about 10 minutes.
Knead the yeast milk with the remaining flour, salt and egg to form a smooth dough. Cover and let rise in a warm place for another hour.
In the meantime, wash the fruit, halve or quarter the plums and remove the stone. Peel the apples, remove the core and cut into slices or wedges. For the crumble, knead the flour, the cold butter, sugar, vanilla sugar and a pinch of salt together until you get the crumble. I stir the ingredients with the mixer until there are only small sprinkles or the longer you stir then the sprinkles get bigger, as everyone likes.
Preheat the oven to 180 ° C O / U heat. Grease the baking sheet or cover with baking paper.
Knead the risen yeast dough briefly and place on the prepared baking sheet, either roll it out or spread it out with your hands. Spread the prepared fruit on top as desired. Then spread the sprinkles over it. Bake the cake in the preheated oven for about 30 minutes, make a stick test.