Perfect Chocolate Chip Cookies

1 tsp baking soda
2 sticks unsalted butter, melted and cooled slightly
1/4 cup white granulated sugar
1 1/4 cup brown sugar
1 large egg
1 large egg yolk
2 Tbs milk
1 1/2 tsp pure vanilla extract
10 oz. semi-sweet chocolate chips

Preheat oven to 375 F.
In a bowl, whisk together the flour, baking soda and salt.  Set aside.
In the bowl of a stand mixer with the paddle attachment, combine the white and brown sugar.  Slowly add the butter with mixer on Low.  Increase speed to Medium and beat for 3 - 4 minutes, until mixture becomes light in color. 
With mixer on Low, add the egg and egg yolk, one at a time, letting each one incorporate fully.
Add the milk and vanilla and fully combine.  Scrape down the bowl and mix again shortly to blend evenly.
With mixer on Low, add about 1/2 cup of flour mixture to the mixing bowl.  Increase speed slightly to incorporate flour and then back speed down to Low again.  Repeat until all the flour has been added.
Lock the head of the mixer.  With speed on Low, add the chocolate chips and fully combine.
Chill the batter for 5 minutes.  After chilling, stir slightly and chill for another 5 minutes.
Using a #40 disher, place 9 balls of dough evenly on a sheet pan and bake for approximately 9 1/2 to 10 minutes, until edges are slightly brown and center is still "doughy".
Let cookies cool on the pan for about 45 seconds to 1 minute, just long enough to prepare another pan of dough balls and get them in the oven.
Remove cookies to a cooling rack and let cool.  Enjoy!