Portuguese Egg Custard Tarts

Make the dough: combine 2 cups all-purpose flour and 1/2 tsp kosher salt in a bowl. Add 1/2 cup ice-cold water and mix until a rough dough forms. Turn onto a floured surface and knead briefly until smooth, about 1 minute. Wrap and chill for 30 minutes.

Roll out the dough into a thin rectangle, spread evenly with half the 1/2 cup softened unsalted butter, fold the dough into thirds like a letter, roll out again, spread with the remaining butter, and fold again. Roll into a tight log, wrap, and chill for 15 minutes.

Make the custard: warm 2 cups whole milk in a saucepan with the 1 cinnamon stick and 1 tsp lemon zest over medium heat until steaming. Do not boil. Remove from heat and steep for 5 minutes; discard the cinnamon stick.

Whisk 2/3 cup granulated sugar and 1/4 cup all-purpose flour (for custard) together in a bowl, then whisk in the warm milk mixture until smooth. Whisk in 6 large egg yolks and 1/2 tsp pure vanilla extract. Strain through a fine-mesh sieve into a pourable container.

Preheat oven to 500°F (260°C). Cut the chilled dough log into rounds about 3/4-inch thick. Press each round into a muffin-tin cup, using your thumbs to spread the dough up the sides.

Fill each shell about three-quarters full with custard. Bake for 10-14 minutes until the custard is set with dark, blistered patches on top and the pastry is golden.

Cool in the tin for 5 minutes, then transfer to a rack. Dust with 1/2 tsp ground cinnamon (for dusting) and serve warm or at room temperature.