Mix the quark with the oil, egg, milk, sugar, salt, lemon zest and vanilla sugar with the hand mixer. Mix flour with baking powder. Stir in half of the flour, then knead in the other half until the dough is smooth and even. Grease a springform pan and roll out the dough in it.
Wash and core the apples, cut into wedges and cover the dough with them.
Mix the flour, sugar and cinnamon. Melt the butter, let it cool and pour it very slowly into the mixed flour, crumbling everything with a fork. Sprinkle the finished crumble on the apples.
Bake at 200 ° C top / bottom heat or 180 ° C hot air for about 25 minutes.