Cookies

http://rasamalaysia.com/butter-cookies-recipe/2

10 oz butter (2 1/2 sticks)
1 tablespoon Pam cooking spray (for baking), optional
1 egg yolk
3 oz + 1 tablespoon powdered sugar
1/4 teaspoon salt
11 oz all-purpose flour
4 oz corn starch
2 tablespoons full cream milk/whole milk
1/2 teaspoon vanilla extract