Portuguese custard tarts (Pastéis de nata)

1. Roll the puff pastry up tightly and cut into 12 equal rounds; lightly butter a 12-hole muffin tin.

2. Place each round cut side down in a hole and, with a wet thumb, press from the centre outwards into a thin case whose edge rises slightly above the tin; chill.

3. Whisk the flour with a third of the milk; bring the rest of the milk to the boil with the lemon peel, stir it into the floury milk and cook until thickened. Boil the sugar with the water for 3 minutes (syrup) and pour it in a thin stream into the milk base; remove the lemon peel.

4. Cool the custard until lukewarm, then beat in the egg yolks thoroughly and strain through a sieve.

5. Fill the cases three-quarters full and bake in the hottest oven possible (250-280 °C, top and bottom heat) for 12-15 minutes until the pastry is crisp and the custard top is scorched in patches.

6. Serve lukewarm, dusted with icing sugar and cinnamon – best on the day.

Tip: The monks of Lisbon's Belém monastery invented them to use up the yolks left over from the egg whites used for starching – the custard only gets its characteristic burnt spots at very high heat, so use your oven's highest setting.