Melt butter at low heat. Mix 350 g flour, 175 g sugar, 1 vanillin sugar and 1 pinch of salt. Add the liquid butter and knead into crumbles with a hand mixer. Sprinkle 1-2 tablespoons of flour on top and shake
Line 2 baking trays with baking paper. Mix quark, milk, oil, 1 egg, 75 g sugar, 1 vanillin sugar and 1 pinch of salt with the whisk of the hand mixer. Mix 300 g flour and baking powder and knead it in with the dough hooks of the hand mixer. Divide the dough into 4 pieces, roll each out to a circle (approx. 18 cm Ø each) on some flour
Place 2 circles on 1 baking tray and spread with jam. Sprinkle the crumbles on top, rubbing or tearing them between your fingers. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/gas: level 3) one after the other for about 20 minutes. Let them cool down
Mix icing sugar, lemon juice and 1 tbsp. hot water. Dribble onto the thalers and leave to dry. To serve, cut into 4 to 6 pieces