Portuguese Egg Tarts

Directions

1. For the puff pastry: In a medium bowl, add half of the butter (1/4 cup + 2 tablespoons or 85g), 3/4 cup (95g) of the flour, and 1/4 teaspoon of salt. Using a pastry cutter or two knives, blend together until it resembles coarse wet sand with some small lumps of butter. Knead just until it form a firm dough ("oil dough"), shape into a flattened disc, cover in plastic wrap, and refrigerate for at least 20 minutes.
2. Meanwhile in a medium bowl, gently whisk together the egg, water, and remaining 1/4 teaspoon salt. Add remaining 3/4 cup (95g) flour and stir with a rubber spatula to form a wet dough ("water dough"). Cover bowl tightly with plastic wrap and refrigerate for 20 minutes.
3. Generously flour a clean work surface. Remove the wet dough from the refrigerator, scrape onto the floured surface, and generously sprinkle with more flour. Using a floured rolling pin, roll dough into a thin 11-inch square, adding more flour as needed.
4. Remove the disc of dough from the refrigerator and crumble on top of the thin rolled out dough, leaving a 3-inch border. Gently fold the exposed edges over the crumbled dough to meet in the middle, covering completely. 
5. Roll out the dough again into an 11-inch square. Fold one third over the center third, and cover with the final third (like a tri-fold letter). Roll rectangle back into an 11-inch square again then repeat folding and rolling two more times (I like to alternate which sides I fold over). After the third time, fold each corner into the center, then roll into a 1/2-inch thick square. Cover in plastic wrap and refrigerate for at least 20 minutes. 
6. When ready, lightly grease the inside of 12 fluted tart molds or a muffins pan; set aside. Roll out chilled dough to 1/8-inch thick. Using a 3-1/2-inch round cutter, cut the dough into 12-rounds, then lightly press into the molds. Place on a rimmed baking sheet and transfer to the refrigerator to chill while you make the egg custard.
7. For the egg custard: Preheat oven to 350F with rack in the venter. 
8. In a medium saucepan over high heat, combine the water. sugar, and cinnamon stick. Bring to a boil, let boil for 1 minute, then remove from heat; set aside to steep.
9. In a small saucepan over medium-low heat, add 1/2 cup (125g) of the milk and heat until scaled (bubbles form around the edges). Remove from heat.
10. In a medium bowl, whisk together the flour and 3 tablespoons of water. While continuously whisking, slowly pour the scalded milk into the flour mixture. Continue to whisk while slowly pouring in the cinnamon syrup, removing the cinnamon stick. 
11. Return mixture back to the medium saucepan and cook over low heat, whisking constantly, until thickened, about 4 minutes. Add egg yolks and salt and whisk to combine. Strain through a fine-mesh strainer set over a large glass measuring cup or bowl with a pour spout.
12. Remove tart molds filled with dough from the refrigerator and evenly space them out on the rimmed baking sheet. Fill each 3/4 full. Carefully transfer to the preheated oven for 30-45 minutes, or until golden on top (will be very puffy).
13. Let cool in molds for 5-10 minutes before carefully removing to cool completely on a wire rack. Best served the same day, warm or at room temperature/ Any leftover should be refrigerated in an airtight container.