In a mixing bowl, combine all-purpose flour and chilled unsalted butter until it resembles coarse crumbs. Add a pinch of salt, sugar, eggs, and ice water. Knead until smooth and elastic, around 5-7 minutes. Wrap in plastic wrap and rest for 15 minutes.

Make oil dough by mixing all-purpose flour, shortening, and additional butter in a separate bowl. Stir until smooth, shape into a square and cover. Rest for 10 minutes.

Roll out water dough into a rectangle. Place oil dough in center, fold water dough over it, and seal. Roll out again and fold into thirds. Wrap and rest for 10-15 minutes.

In a heatproof bowl, mix hot water and sugar until dissolved. Cool it down before mixing eggs and evaporated milk. Strain mixture through a fine sieve.

Preheat oven to 325°F (160°C). Cut pastry dough into circles for molds. Press dough into molds, pour custard mixture into each shell, filling 3/4 full. Bake for 25-35 minutes until set and golden.