Chop nuts for the dough. Mix flour, 175 g sugar, vanillin sugar, cinnamon, nuts and salt. Add 1 egg and butter and knead into crumbles. Put approx. 2/3 of the crumbles into a greased rectangular tart tin (approx. 20 x 28 cm), dust with flour and press to a base with a rim.
Chill the remaining crumbles.
For the quark mixture, mix quark, crème fraîche, 3 eggs, 50 g sugar and sauce powder. Stir in apple sauce. Sprinkle crumble base with crumbs. Add the quark mixture evenly. Bake in a preheated oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: see
manufacturer) on the lowest rack for about 20 minutes. Spread the remaining crumbles on the quark mixture and bake for another 30 minutes. Take out and let it cool down. Remove from the tin and dust with icing sugar.