Step 1

Cream butter with Pam cooking spray (if using), sugar, egg yolk, salt and vanilla extract until fluffy. Add in the milk and mix well.

Step 2

Fold in the all-purpose flour and cornstarch. Using a spatula and your hands to mix the dough. At first, the dough would look crumbly as the picture below.

Step 3

Continue to mix the dough until it becomes soft and not stick on hands, about 10 minutes. Cover the dough with a plastic wrap and chill in the refrigerator for 30 minutes.

Step 4

Preheat oven to 350°F (176°C). Line two baking sheets with parchment paper. Roll the dough to 1/4 inch thick. Cut into rounds or whatever shapes you wish using cookie cutters. Assemble the scrap and roll in with the remaining dough.

Step 5

Place the cookies on the prepared baking sheets and bake for 15 minutes, or until cookies are turn very light brown in color and the inside is cooked through. Cool the cookies before eating. You may keep the cookies in an airtight container for up to two weeks.