Caramelise 100 g sugar in a pan. Turn all nuts in it. Spread on baking paper and cool down
Grease a fat pan (approx. 32 x 39 cm; approx. 3.5 cm deep) and sprinkle with breadcrumbs. Melt the fat, let it cool down a little. Mix 700 g flour, baking powder, 300 g sugar, vanillin sugar and salt. Add the liquid fat and egg yolk and knead everything into crumbles using the dough hooks of the hand mixer
Spread 2/3 of the crumble on the fat pan, press down smoothly with lightly floured hands. Coarsely chop the brittle and knead with the remaining crumbles, except for 4 tbsp.
Peel, quarter and core the apples and cut them into approx. 2 cm thick slices. Mix with 4 tbsp. sugar, lemon peel and juice. Spread on the crumble base. Sprinkle brittle crumbles on top. Bake in the preheated oven (electric oven: 175 °C/circulating air: 150 °C/gas: level 2) for 50-60 minutes. Cool down. Sprinkle with rest of brittle