Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, baking soda, baking powder, and salt.
In a large bowl, cream together the softened butter and sugar until light and fluffy.
Beat in the egg, vanilla extract, and milk until well combined.
Gradually add the dry ingredients to the wet mixture, mixing until a soft dough forms.
Roll the dough into 1 ½-inch balls and coat each ball in the extra granulated sugar.
Place the balls on the prepared baking sheet, about 2 inches apart. Gently flatten each ball with the bottom of a glass.
Bake for 8-10 minutes, or until the edges are set and the centers look slightly underbaked. Let the cookies cool on the baking sheet for 5 minutes before transferring to a wire rack.
