In a small, microwave safe bowl, melt butter.
In a medium bowl sift together flour, salt, and baking soda; set aside.
Add melted butter and both sugars to a medium mixing bowl. Beat on medium speed, using a handheld electric mixer, for 2 minutes.
In a small bowl mix together egg, egg yolk, milk, and vanilla. Slowly add the egg mixture to the butter mixture and beat until well combined. Gradually add flour mixture. Fold in chocolate chips. Chill dough for 1 hour.
Preheat oven to 375 degrees. Adjust the racks in the top third and bottom third of the oven.
Using a medium cookie scoop, form dough into balls, placing 6 balls on each prepared cookie sheet.
Bake in preheated oven, 2 sheets at a time for 15 minutes, rotating halfway in between. Slide the parchment off baking sheet onto a wire rack and cool.