For the crumbles, put flour, 150 g sugar, 1 packet of vanillin sugar, 1 pinch of salt, 1 egg and butter in flakes in a mixing bowl. Knead into crumbles with the dough hooks of the hand mixer. Put half of the crumbles into a greased springform pan (26 cm Ø), press them down to a smooth base and chill. Put the rest of the crumbles in a cool place. Wash, halve and stone the plums.
For the cheese mixture, stir the quark, mascarpone, lemon juice, 100 g sugar and 1 packet of vanillin sugar until smooth. Stir in 3 eggs and pudding powder one after the other. Spread the base thinly with plum jam. Add the cheese mixture and smooth it down. Put plum halves on the quark mixture. Spread the remaining crumbles on top. Bake in the preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for 50-60 minutes. Let cool on a cake rack. Remove the cake from the tin.
Put plum halves on the quark mixture. Spread the remaining crumbles on top. Bake in the preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for 50-60 minutes. Let cool on a cake rack. Remove the cake from the tin. Dust with icing sugar before serving
waiting time approx. 1 1/2 hours