In the bowl of an electric mixer, combine softened butter, powdered sugar and brown sugar. Beat on medium speed until light and fluffy. Scrape down the sides of bowl as needed. Beat in vanilla.
Add flour and mix on low speed until completely combined.
Add chopped chocolate and mix by hand until evenly distributed.
Portion out 1.5-2 tablespoons worth of dough and shape into a ball. Repeat until all cookie dough is used, about 24 cookies.
Chill the dough in the refrigerator for 2 hours.
While the dough is chilling, preheat the oven to 350℉. Line a baking sheet with parchment paper. Set aside.
Remove cookies from the fridge and, if not done already, evenly space them onto a cookie sheet. Leaving about 1 inch of space between each cookie.
Bake for 13 minutes or until edges are lightly browned.
Allow cookies to firm up on the cookie sheet before transferring them to a cooling rack