Grease the springform pan (26 cm Ø; 7-8 cm high). Mix 250 g flour, 150 g sugar, 2 vanilla sugars, salt, nuts, butter in flakes with the dough hooks of the hand mixer to form crumbles. Press 2/3 crumbles in the form of a base. Sprinkle with breadcrumbs. Refrigerate the base and the rest of the crumbles for about 20 minutes.
Peel, quarter and core the apples. Cut the quarters in half and sprinkle with lemon juice
Beat the eggs, 225 g sugar and 2 vanillin sugars with a hand mixer until frothy. Stir in curd cheese, mascarpone, semolina and 1 heaped tablespoon of flour
Dab apples dry and spread on the crumble base. Spread the quark mixture on top. Sprinkle the rest of the crumble over it, crumbling it by hand. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 1 1/4 hours. Leave to cool in the mould. Dust with icing sugar