Caramelize 120 g sugar in a pan without fat. Add nuts and turn in them. Spread on baking paper and let cool down.
Melt the butter and let it cool down a bit. Mix the flour with baking powder, vanilla sugar, salt and 300 g sugar. Add the fat and egg yolk and work everything into crumbles.
Grease a fat pan (approx. 338 cm) and sprinkle with breadcrumbs. Press 2/3 of the breadcrumbs into the drip pan as a base.
Roughly chop the brittle and mix well with the remaining crumble dough except for 4 tablespoon.
Peel and quarter the apples and remove the core. Cut the apples into wedges, mix well with 50 g sugar, lemon juice and zest and spread on the crumble base. Put the brittle crumble on top.
Bake in a preheated oven at 175 degrees (convection 150 degrees) for 50-60 minutes. Let cool down. Sprinkle with the remaining brittle.