For the dough, mix flour, 100 g sugar, vanillin sugar and salt in a mixing bowl. Add oil, 1 egg and 200 g quark. Warm the milk lukewarm, dissolve the yeast in it and also put it into the mixing bowl and knead it with the dough hooks of the hand mixer to a smooth dough.
Cover the dough and let it rise in a warm place for about 45 minutes.
Wash the lemon hot, grate dry and finely grate the peel. Halve the fruit and squeeze the juice. Mix 800 g quark, sour cream, 4 eggs, 175 g sugar, starch, lemon peel and 3 tbsp. lemon juice.
Drain the cherries well. Roll out the dough on a greased grease pan of the oven (32 x 39 cm). Spread cream on the dough and smooth it down. Spread the cherries on top.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 30-40 minutes. Remove from the oven and let it cool down on a cake rack. Stir the jam until smooth and carefully fold into the yoghurt.
Serve yoghurt icing with the cake.