Place the puff pastry sheets next to each other on a baking tray lined with baking paper and allow to defrost for approx. 10 minutes. In the meantime mix pudding powder and sugar. Gradually stir with approx. 3 tbsp. milk until smooth.
Bring the remaining milk to the boil, remove from the heat and stir in the pudding powder with a whisk. Boil the pudding while stirring for about 1 minute, remove from the stove and let it cool down a little.
Drain the peach halves and cut in half. Roll out puff pastry sheets one after the other on a floured work surface (approx. 23 x 23 cm). Quarter each puff pastry sheet. Fold the corners of each puff pastry sheet towards the middle and press on.
Place some pudding in the middle of each plate and place a piece of peach on each. Sprinkle with sugar crystals.
Place the pastry on 2 baking trays lined with baking paper and bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 15-20 minutes, sheet by sheet. Chop the biscuits.
Remove the Danish pastry from the oven and sprinkle with biscuits.