Place the puff pastry slices next to each other and allow to thaw. Bring 350 ml milk to the boil. Stir 50 ml milk, sugar and pudding powder until smooth and add to the boiling milk. Simmer the pudding while stirring for about 1 minute. Cover the surface with foil and chill.
Put the cherries in a sieve and let them drip off. Place puff pastry slices on top of each other and roll out square (approx. 36 x 36 cm). Cut puff pastry into 9 squares (approx. 12 x 12 cm). Mix egg yolk and 3 tablespoons of milk and brush the edges of the puff pastry with it. Wrap 2/3 of the pastry corners in the middle, then fold the long sides halfway. Brush the edges again with egg yolk milk. Stir the pudding until smooth and add 1-2 tablespoons to the middle of each dough. Spread the cherries on top and press down firmly. Place the Copenhagen on 2 baking trays lined with baking paper.
Brush the edges again with egg yolk milk. Stir the pudding until smooth and add 1-2 tablespoons to the middle of each dough. Spread the cherries on top and press down firmly. Place the Copenhagen on 2 baking trays lined with baking paper. Bake the trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 20-30 minutes. Serve Copenhageners lukewarm or cold
30 minutes waiting time