Pastéis de Nata, Portuguese Custard Tarts

Combine sugar and water in a saucepan, add lemon zest and a whole cinnamon stick. Bring to a boil and cook for about 3 minutes until a light syrup forms. Remove from heat and discard the lemon zest and cinnamon stick.

In a smaller bowl whisk plain flour with a little cold milk until smooth. Bring the remaining milk to a boil in the saucepan, then pour in the flour mixture while whisking continuously and cook for about 2 minutes until it thickens slightly. Remove from heat and let it cool a little.

Separate 4 egg yolks and 2 whole eggs from the whites. Lightly beat the yolks and eggs with a fork. Gradually stir the sugar syrup and vanilla extract into the milk mixture, then add the beaten eggs while stirring continuously. Strain the custard through a fine sieve to remove any lumps.

Unroll the puff pastry on a lightly floured surface and roll it into a tight log. Wrap in plastic wrap and refrigerate for 10 minutes to firm up.

Slice the log into 12 equal rounds, about 2 cm thick. Place each round cut side down into a lightly buttered muffin tin and press it evenly with your thumb across the bottom and up the sides so the pastry slightly overhangs the edge. The base should be thinner than the sides.

Place the lined tin in the refrigerator for 15 minutes so the pastry firms up before baking.

Preheat the oven to 250 °C (top and bottom heat). Fill each shell with custard to about three-quarters full, the custard will puff up slightly during baking.

Bake for 15-20 minutes until the pastry is golden and characteristic dark caramelized spots appear on the custard surface. Watch the oven closely, as the difference between perfect caramelization and burning is just a few minutes.

Let the tarts rest in the tin for 5 minutes, then carefully transfer to a wire rack. Serve warm, optionally dusted with ground cinnamon or powdered sugar.