Slice the 1/2 cup (110 grams) of butter for folding in and arrange the slices in a square inside a plastic bag. Use a rolling pin to flatten evenly, then freeze until firm.

Place all crust ingredients in a mixer and blend until no dry flour remains. Add the butter and mix until a dough forms. Wrap in plastic wrap and refrigerate for about 30 minutes.

After chilling, press the dough into a square slightly larger than the butter square from step 1. Place the butter in the center and wrap the dough around it, pinching the seams tightly closed.

Gently roll the dough with a rolling pin from the center outward to form a rectangle. Fold into thirds. Repeat this rolling and folding process at least 3 times (for extra flaky layers, repeat 6 times).

Wrap the finished dough in plastic wrap and refrigerate for 30 minutes.

Roll the dough from step 5 into a thin sheet about 1/8 inch (0.3 cm) thick. Lightly brush the surface with water, then roll up tightly into a log. Wrap in plastic wrap and freeze for at least 30 minutes until firm.

In a saucepan, combine the milk, heavy cream, and sugar. Heat over low heat until the sugar dissolves (do not boil).

Beat the eggs and gradually whisk them into the milk mixture from step 7. Strain the mixture twice through a fine mesh sieve and set aside.

Cut the chilled dough log from step 6 into 20 equal pieces. If the dough is too soft to cut cleanly, freeze it a bit longer until firm.

Take one piece, dust both sides with flour, and roll into a round about 4 inches (10 cm) in diameter, with the center slightly thicker than the edges. Press into a 2 3/4-inch (7 cm) tart cup, making sure the bottom is flat and the sides are smooth with no wrinkles. Repeat to make 20 tart shells.

Pour the strained custard filling into each tart shell, filling each about 80–90% full to prevent overflow during baking.

Place the tarts on the lower rack of a preheated oven at 430°F (220°C) and bake for 25–30 minutes, until the tops are golden brown.

The homemade tart crust bakes up super flaky!