Place puff pastry slices next to each other on the work surface and allow to defrost. Scald peaches hot and peel the skin. Halve the peaches and remove the stones. Cut the flesh into slices.
Wash and stone the cherries. Knead marzipan and lemon juice. Cut the dough slices in half crosswise and roll out a little (approx. 13x13 cm). Spread 1 teaspoon of marzipan on the middle of each square.
Cover with peach slices and some cherries. Fold the pastry corners towards the middle. Whisk the egg yolks and cream. Spread the Kopenhagener with it. Bake in the preheated oven (electric: 200 °C/ gas: level 3) for about 15-20 minutes.
Makes 12 pieces.