Portuguese custard tarts (pastéis de nata)

Ingredients

• Butter for greasing
• 500ml whole milk (preferably gold top)
• Pared zest from 1 lemon
• 1 cinnamon stick
• 70g plain flour
• 485g caster sugar
• 6 large free-range egg yolks
• 2 x 320g packs ready-rolled, all-butter puff pastry

Preparation

1. Grease 22 holes of 2 standard 12-hole muffin tins generously with butter, then chill in the fridge. Put the milk in a pan with the strips of lemon zest and cinnamon. Heat to just simmering, let it cool a little, then remove the zest and cinnamon. Whisk a third of the milk into the flour in a small bowl to form a thin paste. Heat the remaining milk until boiling, then stir in the flour paste and cook, stirring constantly with a balloon whisk, for 2-3 minutes until thick.
2. Put the sugar in a pan with 200ml water. Heat gently to melt the sugar, then turn up the heat and boil for 4-5 minutes until the syrup reaches the short thread stage. Gradually whisk it into the milk mixture to give a white liquid with a similar thickness to double cream. Don’t worry if it’s lumpy.
3. Put the egg yolks in a large bowl and strain over the milk mixture, stirring all the time with the balloon whisk until combined. Set aside with cling film touching the surface.
4. Heat the oven to 250°C/ 230°C fan/gas 9½. Unroll the pastry, remove the plastic lining sheet, then roll it back up. Cut each roll into 11 discs, then put one disc into each greased muffin hole swirl-side up. Carefully press the pastry up the sides with your fingers, working from the centre out, until the pastry just pokes over the top.
5. Pour the custard into the pastry cases to 1cm below the top, then bake in the upper third of the oven for 15 minutes or until the pastry is golden and crisp.
6. Cool in the tin for 5 minutes, then gently lever out the tarts with a spoon and cool on a wire rack.