For the crumbles, melt 375 g fat, cool for about 5 minutes. Mix 500 g flour, 250 g sugar and salt. Slowly knead the liquid fat with the dough hooks of the hand mixer. Cover and chill for approx. 45 minutes
Knead 300 g flour, 200 g fat in pieces, 100 g sugar, vanillin sugar and egg first with the dough hooks of the hand mixer and then briefly with your hands until smooth. Cover and chill for about 30 minutes.
Grease a baking tray (approx. 35 x 40 cm). Roll out the dough on it with a lightly floured dough roll. Spread jam, except for 2 tbsp. Spread crème fraîche on the jam. Spread crumbles as a thick layer on top. Bake in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for about 40 minutes. Let the cake cool down
Stir icing sugar and 3-4 tablespoons of water until smooth. Spread the icing and the rest of the jam generously on the cake. Let the icing dry. Cut the cake into about 20 lozenges