- On a lightly floured surface, roll out the dough into a 33 cm (13-inch) square. With a brush, cover the entire surface of the dough with the butter. Roll up tightly and cover in plastic wrap. Refrigerate for 30 minutes.
- Cut the ends of the roll. Cut into 14 slices.
- On a floured work surface, thinly roll out each slice with a rolling pin. With your hands, line Portuguese tart pans (see note). If the dough is too large, cut off the excess with scissors. Refrigerate while preparing the filling.
- With the rack in the middle position, preheat the oven to 270 °C (525 °F) (see note).
- In a saucepan off the heat, combine the sugar and cornstarch. Add the egg yolks and egg and whisk until smooth. Add the milk, corn syrup, vanilla and cinnamon stick. Mix thoroughly.
- Bring to a boil over medium heat, whisking and scraping the bottom and sides of the pan. Simmer until the mixture has thickened. Remove from the heat. Strain through a sieve.
- With a 45 ml (3 tbsp) ice cream scoop, spoon the filling into the tart pans. Smooth out the top of the filling with the back of a spoon.
- Bake immediately for 13 to 15 minutes or until the top is caramelized and the crust is crispy. Let cool before unmoulding.
- Generously dust with cinnamon before serving.
Portuguese tart pans can be found in most Portuguese grocery stores.
In a pinch, you can make these tarts in muffin tins. You can bake the tarts at 260 °C (500 °F) if your oven reaches that temperature, and finish under the broiler if you do not find that the custard is brown enough. The next day, warm up the tarts in a warm oven for about 5 minutes. They will be as good as the day before.