1. Preheat oven to 475°F (245°C) and grease a 12-cup muffin tin.

2. Roll out puff pastry and cut into 12 rounds to fit the muffin tin cups. Press into cups and chill while making the custard.

3. In a small saucepan, whisk together milk and flour until smooth. Cook over medium heat, stirring constantly, until thickened. Remove from heat.

4. In another pan, combine sugar, water, cinnamon stick, and lemon peel. Boil without stirring until syrup reaches 220°F (104°C). Remove from heat and discard cinnamon and lemon peel.

5. Slowly whisk sugar syrup into the milk mixture.

6. In a bowl, lightly whisk the egg yolks, then gradually add the warm milk mixture while whisking.

7. Strain custard through a sieve to remove lumps.

8. Pour the custard into the chilled pastry cups, filling almost to the top.

9. Bake for 12–15 minutes, or until the tops are caramelized and the pastry is crisp.

10. Let cool slightly, then dust with powdered sugar and cinnamon before serving warm.