Preheat the oven to 325° F. Line rimmed baking sheets with parchment paper and set them aside.
In the bowl of a stand mixer fitted with the whisk attachment, add the flour, baking powder, baking soda and salt; whisk to combine. Switch to the paddle attachment and add the butter, sugar, egg, vanilla and milk, beating well after each addition.
Chill the dough for 1 hour or more in the refrigerator.
Scoop dough with a spoon onto the prepared baking sheets, gently flattening the top of each raw cookie. Space about 1 inch apart.
Bake for 15 to 17 minutes or until the cookies are a golden color. Cool for a few minutes on the baking sheets before moving to a wire rack to cool completely.