Preheat oven to 350ºF (180ºC). Butter baking sheets or line them with parchment paper.
Beat ½ cup unsalted butter with ½ cup white sugar and ½ cup light brown sugar in a large bowl until creamy. You can use a stand mixer or a hand-held, electric one.
Add 1 egg and 1 teaspoon vanilla extract and mix well.
Add sifted dry ingredients (1 ⅔ cups all-purpose flour, ½ teaspoon baking soda, pinch of baking powder and ¼ teaspoon salt) and mix until a few dry spots remain. Don’t overbeat at this point.
Add 1 cup milk chocolate chips and mix until no dry spots remain. I like to switch to a spatula for this part.
Scoop portions of cookie dough and place them on the prepared baking sheets, spacing about an inch and a half.
Press on top of each cookie to flatten slightly. You can add a few extra chocolate chips to each cookie before baking.
Bake for about 10 minutes, until edges are firm and cookies are a light golden brown but still soft in the center. It might take a minute or two more if you make larger or thicker cookies. If you like crispy cookies, bake a minute or two more.
Let the baked cookies cool completely on a cooling rack.
Keep in tins or cookie jars.