In a large bowl, or bowl of stand mixer fitted with paddle attachment, cream together the butter and sugar until smooth and fluffy. About 2-3 minutes.
Beat in the egg and vanilla until well combined.
In a medium bowl whisk together the flour, baking soda, baking powder and salt until combined.
Using a hand mixer or stand mixer on low speed gradually add the dry ingredients to the wet ingredients until the dough comes together.
Drizzle in the milk, 1 Tablespoon at a time until dough is soft, not wet.
Cover the dough and chill for 20 minutes, and up to 24 hours.
Preheat the oven to 350 degrees.
Line a large baking sheet with parchment paper or a Silpat liner.
Roll rounded Tablespoons of dough into balls and place on prepared baking sheet 2 inches apart.
Bake in preheated oven for 10-12 minutes.
Move the cookies to a wire rack and allow to cool completely before frosting as desired.
NOTE ON MAKING AHEAD: You MUST chill this dough for at least 30 minutes for best results, and can refrigerate for up to 24 hours. This dough can be frozen for up to 3 months. Thaw in the refrigerator overnight before baking.