Place puff pastry sheets next to each other and allow to thaw at room temperature for 20-30 minutes. In the meantime, clean and wash the gooseberries. Bring 150 ml water, sugar, cinnamon stick, lemon peel and cassis liqueur to the boil.
Add gooseberries to the stock and steam for 3-5 minutes. Lift out with a skimmer and drain. Stir cornflour and a little water until smooth and add to the boiling stock. Bring to the boil again briefly and pour over the gooseberries.
Let it cool down a little. In the meantime, moisten the puff pastry sheets slightly with water, place them on top of each other and roll them out into a large rectangle (20x50 cm) on a floured work surface. Cut out 10 squares (10 x 10 cm).
Cut all corners about 4 cm deep and fold half of each corner to the middle. Put 1 tablespoon of gooseberries in the middle and place them on 2 baking trays lined with baking paper. Mix egg yolk and cream and brush the wings of the windmills with it.
Bake in the preheated oven (electric oven: 200°C/ gas: level 3) for about 10 minutes one after the other. Let cool down on a cake rack. Results in 10 pieces.