Clean, wash, halve and stone the plums
Mix quark, 4 tablespoons milk, oil, 50 g sugar, 1 sachet vanillin sugar and salt. Mix flour and baking powder. Stir half into the quark mixture, knead in the rest
Roll out the dough on a lightly floured work surface until round (approx. 32 cm Ø) and place in a greased tart or springform pan (approx. 28 cm Ø). Press the edge of the dough against the edge of the tin
Spread the plums close together (e.g. in flakes) on the dough and press slightly
Coarsely chop the walnuts. Melt 100 g sugar and 1 packet of vanillin sugar in a frying pan. Add butter and 1 tablespoon of milk and bring to the boil while stirring. Fold the walnuts into the caramel mass. Spread the walnut brittle on the plums
Bake the cake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 ° C / gas: level 3) for 45-50 minutes (cover with parchment paper after about 20 minutes) Take the cake out of the oven and let it cool down. If necessary, decorate with cream and lemon balm