Grease a springform pan (26 cm in diameter). Preheat the oven to 180 ° C top / bottom heat or 160 ° C convection.
Quickly knead crumbs from the butter, sugar, egg, vanilla sugar, flour and baking powder. Cover the springform pan with half of the crumbs.
Peel the apples, remove the core and cut into wedges. Place the apple wedges on the crumbs and dust with cinnamon. Scatter the remaining crumbs on top.
Bake the crumb cake in the oven on the middle rack for about 50 minutes, until the surface is nicely browned. Let cool down before cutting. Cut into 12 pieces.