Cut butter into cubes and freeze for about 30 minutes to an hour.
In a bowl, whisk together flour, salt, and sugar and chill in the refrigerator for about 30 minutes.
Add butter to flour mixture. Cut the butter into the flour using a pastry blender or by pinching the fat into the flour mixture with hands. Work them together until resembling coarse cornmeal with pea-like, butter-speckled pieces.
Slowly drizzle ice water to the flour-butter mixture and with hands, mix until just combined. Gently gather dough and press into a ball. If the dough is too crumbly and does not hold together, add more water a tablespoon at a time. DO NOT ADD TOO MUCH LIQUID and DO NOT OVERWORK DOUGH.
Wrap dough with plastic wrap and chill in the refrigerator for about 2 hours.
Meanwhile, In a bowl, combine egg yolks, evaporated milk and condensed milk until blended. Using a cheesecloth, strain custard mixture.
Divide dough into 12 balls. Place each ball between two sheets of parchment paper and with a rolling pin, gently flatten each ball into 4-inch diameter and 1/8-inch thickness.
Spray holes of a 12-hole muffin pan with nonstick cooking spray. Lift each flattened dough and place into each muffin holes and with hands, gently press on sides and bottom. Trim off excess dough on edges.
Pour custard mixture into prepared dough-lined muffin pan up to 3/4 full and bake in a 350 F oven for about 20 to 25 minutes or until crust is golden and a toothpick inserted in the middle of custard comes out clean.
Remove from oven and allow to cool before removing from pan. Best served at room temperature.