Mix butter, brown sugar, and granulated sugar together until well-combined.
Stir in egg, egg yolk, and vanilla until well-combined.
Add flour, salt, and baking soda. Stir in until just combined.
Stir in chocolate chips until just incorporated.
Cover, and chill dough for at least 30 minutes.
Preheat oven to 325 F. Line baking sheets with parchment paper or silicone baking mats.
Drop cookies by 1/4 cup scoop, spacing dough about 3 inches apart.
Bake for 15-20 minutes, or until edges are light brown and middles are just set.**
Let cookies cool on cookie sheet before removing.
*Butter should be just melted but not hot. It takes me about 40 seconds in the microwave.**If you wait until the tops are light golden brown to take the cookies out, you'll end up with a crunchier cookie.***I sprinkled a little kosher salt on the cookies for pictures (and for me). Feel free to try it or not. ****Nutrition values are estimates.