For the crumbles, roast hazelnut kernels in a pan without fat, then chop them finely. Melt 200 g butter. Knead 300 g flour, 150 g sugar, vanillin sugar, hazelnuts and butter with the dough hooks of the hand mixer to crumbles. Put the crumbles in a cool place. Peel apples, cut out cores.
Cut apples into rings (about 0.5 cm thin). Sprinkle rings with lemon juice. Mix 300 g butter, 300 g sugar and 1 pinch of salt with the whisk of the hand mixer. Stir in the eggs one after the other. Mix 400 g flour, pudding powder and baking powder and stir in alternately with the milk. Put the sponge mixture into the greased fat pan of the oven (32 x 39 cm) and smooth it down. Spread apple rings evenly on top. Mix cinnamon and 2 tablespoons of sugar and sprinkle over the apple rings. Sprinkle crumbles over them and bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 35-45 minutes.
Mix 400 g flour, pudding powder and baking powder and stir in alternately with the milk. Put the sponge mixture into the greased fat pan of the oven (32 x 39 cm) and smooth it down. Spread apple rings evenly on top. Mix cinnamon and 2 tablespoons of sugar and sprinkle over the apple rings. Sprinkle crumbles over them and bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 35-45 minutes. Remove from the oven, place on a cake rack and allow to cool