Beat the butter, sugar, vanilla sugar and salt with a hand mixer until frothy until the sugar has dissolved. Fold in the 4 eggs until a bound mass has formed. Mix the flour with the baking powder and stir in one after the other.
Line a baking sheet with parchment paper and spread the dough evenly on it. Preheat the oven to 160 ° C fan oven.
Now spread the jam evenly on the dough as desired.
For the crumble, put the remaining ingredients in a bowl and use the dough hook of the hand mixer to make crumbles and spread over the jam.
Put the tray in the oven and bake for about 25 minutes.