Peel, quarter, core and cut apples into large pieces. Sprinkle with lemon juice. Mix pudding powder and 50 ml apple juice. Boil up the rest of the apple juice. Stir in the mixed powder.
Add apple pieces and simmer for 3-4 minutes. Pour into a bowl and let cool off. Place the puff pastry slices next to each other and let them thaw. In the meantime whisk marzipan, 2 egg yolks and 6 tablespoons of condensed milk. Place 2 slices of pastry on top of each other and roll out into a rectangle (18 x 11 cm) on a floured work surface. Spread all rectangles evenly with marzipan mixture and fold the corners inwards. Cover evenly with apple compote. Whisk 1 egg yolk and 1 tablespoon of condensed milk and brush the edges of the dough with it. Place Copenhagen on 3 baking trays lined with baking paper. Sprinkle with almond slivers.
Cover evenly with apple compote. Whisk 1 egg yolk and 1 tablespoon of condensed milk and brush the edges of the dough with it. Place Copenhagen on 3 baking trays lined with baking paper. Sprinkle with almond slivers. Bake the baking trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 15-20 minutes. Remove from the oven and allow to cool on a cake rack. Serve decorated with mint
1 1/2 hours waiting time