Knead fat, 150 g flour, 75 g sugar and muesli into crumbles. Chill. Drain the cherries and collect the juice. Mix 100 ml juice and starch. Bring the rest of the juice to the boil, stir in the mixed starch, bring to the boil and simmer for about 1 minute while stirring.
Fold in the cherries. Mix 150 g flour, baking powder, 50 g sugar, salt and vanillin sugar. Add quark, oil and milk. Knead everything smooth. Roll out the dough on a floured surface to a circle (approx. 26 cm Ø).
Grease a springform pan (24 cm Ø) and sprinkle with flour. Put the dough into it, pull the rim up a little and press it on. Pour in cherry compote. Spread crumbles on top. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 35 minutes.