For the short pastry, put 400 g flour, 175 g sugar, 1 packet of vanilla sugar, 1 pinch of salt, 1 egg, 200 g butter in pieces and 3 tablespoons of cold water in a bowl. Knead first with the dough hooks of the mixer, then quickly with your hands to a smooth dough. Wrap in foil and chill for approx. 45 minutes.
For the compote, wash, peel, quarter, core and chop apples. Boil them up with 75 g sugar, lemon juice, cinnamon and 100 ml water. Simmer for about 5 minutes until the apples crumble. Mash finely and let cool.
Roll out the short pastry on the floured work surface to the size of the fat pan. Carefully place the pastry in the greased and breadcrumbs-spread fat pan (approx. 32 x 39 cm) and pull it up slightly at the edge.
For the meringue, beat the 8 egg whites until stiff, add 250 g sugar and continue beating until the sugar is completely dissolved.
Spread the compote on the dough, spread the beaten egg white on top. Bake in the preheated oven (electric oven: 175 °C/circulating air: 150 °C/gas: see manufacturer) on the bottom shelf for 25-30 minutes.
For the crumbles, meanwhile, knead 300 g flour, 175 g sugar, 1 packet vanilla sugar, 1 pinch of salt and 175 g butter in pieces with your hands to form crumbles. Sprinkle on the cake and bake on the middle shelf at the same temperature for another 30 minutes. Let it cool down. Serve dusted with icing sugar.