Tartlets with custard

Ingredients:

Puff pastry

• 165g chilled unsalted butter, cut into 2.5cm cubes, plus extra for greasing pans
• 1.5 cups premium flour + extra for working with the dough
• 1 large egg
• 2 tablespoons of water

Egg custard

• 0.5 cups of sugar
• 1 cup of water
• 4 large eggs
• 1/4 cup unsweetened condensed milk
• 0.5 tsp vanilla extract
• A pinch of salt

Preparation:

1. Puff pastry:
   
   In a medium bowl, beat the butter into 3/4 cup flour with a fork, then knead with your hands until the dough comes together. Transfer the "butter dough" to a piece of plastic wrap and form it into an 7-inch (18.5 cm) square; wrap in plastic wrap and refrigerate for 20 minutes.
2. Meanwhile, in a separate bowl, combine the egg, water, and the remaining 3/4 cup flour. Then, knead with your hands until the dough comes together, adding more flour if it's too sticky. Transfer the "water dough" to a piece of plastic wrap, wrap it in plastic wrap, and refrigerate for 20 minutes.
3. Unroll the "water dough" and roll it out on a lightly floured work surface into a 27.5 cm square. Place the "butter dough" square on top and rotate it so it forms a diamond shape. Fold the sides of the bottom dough over the "butter dough" to completely enclose it.
4. Roll the folded dough into a 27.5 cm square and mark it into thirds. Fold the side thirds over the center, like a letter. Roll the folded dough out again into a larger square. Repeat this process twice (folding like a letter, then rolling out into a square), chilling the dough if it becomes too soft.
5. Draw three parallel lines on the dough, dividing it into quarters. Fold the outer quarters into the center, then fold the dough in half like a book and roll it out again. Wrap the dough in plastic wrap and refrigerate for at least 20 minutes.
6. Grease 12 6-7 cm fluted tartlet pans with butter. Unroll the dough and roll it out on a lightly floured work surface to a thickness of 0.5 cm. Using a round cookie cutter, cut circles from the dough (about 0.5 cm larger than your tartlet pans). Refrigerate for 20 minutes, then spoon the dough into the pans. Refrigerate until ready to bake.
7. Prepare the egg custard:
   
   In a saucepan over medium heat, combine the sugar and water and heat until the sugar dissolves, 3-5 minutes. Let cool completely. Whisk the eggs into the cooled sugar syrup, then add the unsweetened condensed milk, vanilla extract, and salt. Stir. Strain through a sieve into a large measuring cup.
8. Preheat the oven to 175°C. Line the tartlet cases with the dough on a baking sheet. Divide the cream among the tartlets, filling each one three-quarters full. Don't overfill, or the tartlets may overflow. You may have some cream left over.
9. Bake until the tartlets are golden brown and the filling is slightly set, about 45 minutes. Let cool in the pans for 5-10 minutes, then gently tap the bottoms and transfer the tarts to a wire rack to cool completely.