Place the puff pastry slices next to each other and defrost. Finely dice dates, grate marzipan. Wash apples, peel and quarter them as desired, cut out the core. Cut the fruit flesh into small cubes. Mix with lemon juice and sugar. Steam covered for about 5 minutes. Mix marzipan and dates into the apples.
Spread the mixture on the dough slices. Brush 2 opposite tips with egg white and lay on top of each other. Place 5 pieces of dough on a baking tray lined with baking paper. Brush with egg white again and sprinkle with almond flakes. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 17-20 minutes. Allow to cool slightly and dust with icing sugar