Preheat your oven to 350°F (175°C).
In a large mixing bowl, add the softened butter, granulated sugar, and brown sugar. Beat on medium speed until light and fluffy, about 2-3 minutes.
Add the whole egg, egg yolk, and vanilla extract. Mix on low speed until fully combined.
In a separate bowl, whisk together the all-purpose flour, baking soda, and kosher salt.
Gradually add the dry mixture to the wet mixture, mixing on low speed until just combined.
Fold in the semi-sweet chocolate chips until evenly distributed.
Cover the bowl with plastic wrap and chill the dough in the refrigerator for at least 30 minutes.
Line a baking sheet with parchment paper.
Using a cookie scoop or tablespoon, drop rounded balls of dough onto the baking sheet, spacing them about 2 inches apart. Bake for 10-12 minutes.
Let the cookies cool on the baking sheet for about 5 minutes before transferring them to a cooling rack.
