Line a baking sheet with parchment paper or a silicone baking mat and preheat oven to 350°F (180°C).
In a stand mixer with the paddle attached, beat butter, vanilla and both sugars until well combined. The mixture will get a bit light and fluffy. Beat in the egg.
Add flour, baking powder and salt, and stir to combine. Add the milk if you think the mixture seems a little dry. Add chocolate chips and stir just until they're dispersed evenly.
Drop large scoops (about 2-3 tablespoons) of mixture onto prepared baking sheet, about an inch apart.
Bake for 10-15 minutes, or until just beginning to brown around the edges. The cookies should still feel soft, but they will firm up a bit as they cool.