Mix the flour, 300 g sugar, 1 pinch of salt, 1 bag of vanilla sugar, baking powder, ground almonds and cinnamon. Add the egg yolk and the fat in flakes. Knead everything and process into sprinkles.
Grease the oven pan and sprinkle with flour. Put about 3/4 of the crumble in the drip pan and press evenly with your hands to a base. Then bake in the preheated oven (electric stove 175 degrees, gas level 2) for about 15 minutes.
Mix the eggs, 1 bag of vanilla sugar, crème fraîche, 125 g sugar and custard powder. Take the bottom out of the oven, cover with the plums and pour the icing over it. Sprinkle with the remaining crumble and bake for another 45 minutes at the same temperature. Take out and let cool down.