Preheat the oven to 350℉. Line a baking sheet with parchment paper.
In a medium bowl, use a hand mixer to combine the butter, brown sugar and white sugar until creamy (about 1 minute). Add the egg yolk and vanilla and beat until well combined, about 30 seconds. Scrape down the sides of the bowl, as needed.
Add the flour and baking soda and mix on low speed for 10 seconds to just combine the flour, then stir in chocolate chips until evenly distributed and no dry flour remains.
Scoop the dough into six balls and place on the prepared baking sheet about 3-inches apart. Bake 12 to 14 minutes, or until the cookies are golden brown around the edges and just set in the center.
Cool on the baking sheet for 10 minutes before transferring the cookies to a wire rack to cool for another 10 minutes. Enjoy warm or at room temperature.