Preheat the oven to 180 degrees top/bottom heat. Line the deep baking tray with baking paper (if you wet it and crumple it, it will be easier to place in the pan).
For the dough, put the above ingredients in a bowl and knead into a crumble dough. Pour 2/3 of the dough into the baking pan and press it down. You can get the base nice and smooth with a small dough roller (cake pan roller). A spoon or a glass with a flat bottom will also do. Cool the mold until further use.
For the filling, wash and pit the plums and cut the halves into six parts. Mix eggs and sugar with a whisk. Add curd cheese, yogurt, cream and vanilla paste and mix. Fold in the custard powder.
Spread the quark mixture on the crumble base. Add the plum pieces on top. Sprinkle the rest of the dough on top of the mixture.
Bake the cheesecake in the preheated oven for about 45 minutes. The center may still jiggle slightly. The mixture will then firm up after cooling. Open the oven slightly and let the cheesecake cool in the oven. The cake is best cut when it is well cooled.
