Pour the melted butter int he mixer's bowl. Add the sugars. Cream butter and sugar on medium speed. Add the egg, egg yolk, millk and vanilla and mix until well combined. Slowly incorporate the flour mix until thoroughly combined. Stir in chocolate chips.
Chill the dough then scoop onto parchment-lined sheets, six per sheet. Bake at 375° for 12-14 minutes or until golden brown.