Preheat the oven to 430°F/ 220°C. Line a baking sheet with parchment paper.
Unroll the puff pastry on the working surface. Sprinkle evenly with sugar and cinnamon.1 sheet puff pastry + ⅓ cup granulated sugar + 1 teaspoon cinnamon
Fold the left and the right sides of the dough inward so they meet in the center.
Cut into ¾ inch/ 1.5 cm thick slices; you will have about 24-26 palmiers.
Bake French palmiers: Place on the prepared baking sheet and bake for 10-11 minutes or until crispy and golden.
Leave to rest on the tray for 2 minutes, transfer to wire racks to cool.
Notes
Puff pastry: Sheets of frozen puff pastry can be used instead. Defrost for about 30 minutes before filling and cutting or use according to the packet's instructions.