Grease a springform pan (26 cm Ø) and dust with flour. Roast ground hazelnuts in a pan without fat, take them out immediately and let them cool down. Mix flour, roasted hazelnuts, 150 g sugar, 1 packet of vanillin sugar and salt in a bowl. Add 1 egg and butter. First knead into crumbles with the dough hooks of the hand mixer, then with your hands. Weigh 300 g crumbles and set aside. Put the rest of the crumbles into the mould, press to a smooth base and a rim of about 2 cm
Cut the mango off the stone. Peel the flesh and dice finely. Mix quark, crème fraîche, 75 g sugar, 1 sachet vanilla sugar, 4 eggs, lemon juice and grated rind to a smooth cream. Sprinkle starch over it and stir in. Fold a good half of the mango cubes into the quark cream. Put the quark cream into the mould, smooth it down and sprinkle with the remaining mango cubes
Bake in the preheated oven, lower shelf (electric oven: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 50 minutes. Coarsely chop the hazelnut kernels and mix with the remaining crumbles. After approx. 25 minutes spread the crumbles on the cake and bake. Let the cake cool down in the tin on a cake rack. Dust with icing sugar as desired
Waiting time approx. 15 minutes