For the cookie crust: Beat 1/3 cup unsalted butter (65g) and 1/3 cup powdered sugar (40g) together until smooth and fluffy. Sift in 1 1/4 cups cake flour (150g), add 1/4 teaspoon salt (1g) and 1 1/2 tablespoons beaten egg (20g), and mix until combined. Knead by hand to form a dough. Roll out the dough, then wrap tightly in parchment paper or plastic wrap and refrigerate for 1 hour.

For the egg tart filling: Mix scant 1/2 cup hot water (100g) and 1/4 cup granulated sugar (40g) until the sugar dissolves, then let cool. Beat 3 large eggs, add the cooled sugar water, and mix until combined. Strain the egg mixture twice and set aside.

For the cookie crust: Take out a portion of the dough, roll it flat, and press it into tart molds to form the crusts. Refrigerate the crusts for another 30 minutes.

Remove the tart shells from the refrigerator and carefully pour the egg mixture into each shell.

Bake at 350°F (180°C) for 15 to 20 minutes, until the filling is set.