Preheat oven (electric cooker: 225 °C/circulating air: 200 °C/gas: see manufacturer). Coarsely grate marzipan on a kitchen grater. Add sour cream and mix with the Schneeb
Wash the apples and prick out the core. Slice or cut the apples into thin slices. Sprinkle with lemon juice immediately.
Line a baking tray with baking paper. Unroll puff pastry and remove paper. Roll out a little thinner (approx. 28 x 32 cm) on a slightly floured work surface. Place on the baking tray and pull up slightly at the edge.
Prick the dough several times with a fork.
Spread the dough with the marzipan mixture. Spread apple slices on top and sprinkle with sugar. Bake in a hot oven for 15-20 minutes. Warm up the quince jelly. Spread the quince jelly on the tart while still hot. Let it cool down.