Work the flour, baking powder, sugar, vanilla sugar, quark, milk, oil and salt into a dough and spread on a baking sheet. Line the baking sheet with parchment paper beforehand. Spread the peaches evenly on the dough.
Beat the remaining ingredients for the topping with the mixer and pour over the peaches.
Bake the whole thing with top and bottom heat at 180 degrees for about 30 minutes.