Yield: 12 tarts.
For the crust:
2 cups all-purpose flour
1 teaspoon salt
3 tablespoons sugar
8 ounces unsalted butter, cubed and frozen
¼ cup ice water
For the custard:
6 egg yolks
1 (12-ounce) can evaporated milk
1 ( 14-ounce) can sweetened condensed milk
½ teaspoon freshly grated nutmeg
In a bowl, whisk together flour, salt, and sugar, and chill in the refrigerator for about 30 minutes.
Add frozen butter cubes to flour mixture. Cut the butter into the flour using a pastry blender or by pinching it into the flour mixture with your hands. Work them together until the mixture resembles coarse cornmeal with pea-size pieces.
Slowly drizzle ice water into the flour-butter mixture and mix with hands until just combined. Gently gather dough and press into a ball. If the dough is too crumbly, add more water one tablespoon at a time. Be careful not to overwork dough. Wrap dough with plastic wrap and chill in the refrigerator for at least 30 minutes or up to 2 hours.
Meanwhile, in a bowl, combine egg yolks, evaporated milk, condensed milk, and nutmeg until blended. Using a cheesecloth, strain custard mixture.
Preheat oven to 350°.
Evenly divide dough into 12 balls. Place each ball between two sheets of parchment paper and use a rolling pin to gently flatten each ball into discs, 4-inch diameter and ⅛-inch thickness.
Prepare a mini muffin pan with cooking spray. Place one disc of dough into each muffin cup and gently press on sides and bottom. Tuck or pinch dough around edges.
Fill each pastry with custard until ¾ full.
Bake for about 20 to 25 minutes or until crust is golden and a toothpick inserted in the center of custard comes out clean.
Remove from oven and allow to cool before removing from pan. Best served at room temperature.