Ultimate Chewy Chocolate Chip Cookie

These cookies stay chewy even after a round in the fridge!

1 1/4 c brown sugar
1/4 confectioner's sugar
2 1/4 c bread flour
1 t baking soda
1 1/2 t vanilla
2 sticks unsalted butter
2 T milk
1 egg
1 egg yolk
2 cups chocolate chips

Place oven rack into middle position. Preheat oven to 350 degrees. In a small saucepan, melt butter on low heat.  Be careful not to let butter brown.  Meanwhile, sift baking soda and flour together into a separate medium bowl.  When butter is melted, pour into mixing bowl with sugars and beat until well-incorporated (about 1 1/2 minutes).  Beat in egg, egg yolk, milk, and vanilla (30 seconds to 1 minute).  Slowly wisk in flour 1/2 cup at a time.  Fold in chocolate chips.  Cover dough and refrigerate until hardened (about 20 minutes).  Form dough into 1 1/2-inch balls and place on an ungreased cookie sheet, leaving about 3 inches between each dough ball.  About six cookies will fit on a standard cookie sheet.  Bake about 10 minutes, or until the cookie edges are just toasted.  Transfer to wire rack for 5 minutes before serving.