Here's a super easy and delicious egg tart cookie recipe video. First, soften the unsalted butter at room temperature and cream it well with the powdered sugar. Next, add the beaten egg in several batches, mixing quickly to prevent separation. Sift in the cake flour, skim milk powder, and salt, and mix with a rubber spatula using a cutting motion until a dough forms. Roll the dough into 13g balls and shape them into egg tarts by making a small indentation in the center with a teaspoon. While the tarts are chilling in the refrigerator, mix the egg yolks, sugar, and milk to make the filling. Pour the filling into the indented tarts and bake in a preheated oven at 170°C for 20 minutes. You'll have delicious egg tart cookies with a crispy cookie crust and smooth custard filling, and they're also cute to look at!