Scald and skin peaches hot. Cut in half and remove stone. Cut fruit halves into slices. Stir quark, sugar, vanillin sugar, milk, oil and salt until smooth. Mix flour and baking powder, stir gradually into the quark mixture.
Finally knead into a smooth dough. Grease a tart mould with removable base (28 cm Ø) and dust with flour. Roll out the dough round (approx. 32 cm Ø), place it in the tin and press it down.
Spread peach slices spirally on top. Warm the jam and spread on the peaches. Bake the tart in the preheated oven (electric: 200 °C/ gas: level 3) for 25-35 minutes in the lower third.
Let it cool down and sprinkle with sugar crystals. Serve with sour cream. Makes about 12 pieces.