Place the puff pastry slices next to each other and let them thaw. Mix sugar and cinnamon. Melt butter. Roll out puff pastry slices one after the other to a square (22x22 cm) on a floured work surface. Brush with butter and sprinkle evenly with the sugar and cinnamon mixture. Roll up the puff pastry from both sides to the middle and press together.
Brush the puff pastry rolls with butter and sprinkle with sugar crystals. Cover 2-3 baking trays with baking paper. Cut each roll into about 20 slices. Press the slices flat with your fingers and spread them on the baking trays. Bake one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 15 minutes. Place the baking trays on the cake rack and let them cool down
Waiting time approx. 30 minutes