Preheat oven to 350ºF. Combine butter and sugars in the bowl of a stand mixer. Beat on low until combined, then gradually increase to medium-high (setting 6 on a KitchenAid) and set timer for 5 minutes, pausing once to scrape down sides and bottom of mixer bowl.
Beat in egg and vanilla extract and beat on medium-low speed until fluffy without any wet streaks, about 1 min. Again, pause to scrape down the bowl.
BReduce mixer speed to low and incorporate flour mixture to just combine, scraping down mixer bowl again once or twice. Stir in chocolate chips.
Using 1 ½ tbsp of dough for each cookie, roll into balls. Place about 3 in apart on 2 parchment paper–lined baking sheets. Bake one sheet at a time in centre of oven until edges are golden and centres appear slightly paler but not wet; 9-11 minutes.
Remove pans from oven. Immediately bang the pan sharply on the counter to deflate cookies them if they’re puffy in the middle. Use a spoon or rim of glass overturned glass to gently re-shape the cookies into perfect circles. and press in a few more chocolate chips if you like.
Let cool for 5 minutes on the pan before transferring to wire racks to cool completely.