Mix 3 tablespoons of milk, sugar and pudding powder. Boil up the rest of the milk. Whisk 1 egg yolk. Stir in pudding powder and egg yolk. Bring to the boil again.
Remove from the heat, cover and let cool off. In the meantime, place puff pastry sheets next to each other and thaw on a floured work surface. Roll out the puff pastry sheets to a length of approx. 24 cm and then cut them in half to form two 12x12 cm squares. Whisk cream and remaining egg yolk. Spread the pastry sheets with it. Fold the corners inwards and carefully press a depression in the middle. Coat the folded corners with egg yolk as well. Fill the vanilla pudding into the hollow. Bake in the preheated oven (electric: 200 °C/ gas: level 3) for 20 minutes. Let the Copenhagen cake cool down.
Fold the corners inwards and carefully press a depression in the middle. Coat the folded corners with egg yolk as well. Fill the vanilla pudding into the hollow. Bake in the preheated oven (electric: 200 °C/ gas: level 3) for 20 minutes. Let the Copenhagen cake cool down. Wash the strawberries, dab dry, clean, cut in half and spread on the Copenhageners. Dust with icing sugar