Pour the melted butter in the mixer's work bowl. Add the sugar and
brown sugar. Cream the butter and sugars on medium speed. Add
the egg, yolk, 2 TBS milk and vanilla extract. Mix until well
combined. Slowly incorporate the flour mixture until thoroughly
combined. Stir in chocolate chips.
Chill the dough, then scoop onto parchment lined baking sheets, 6
cookies per sheet. Bake for 14 minutes or until golden brown,
checking the cookies after 5 minutes. Rotate the baking sheet for
even browning. Cool completely and store in an airtight container.