In a medium bowl, cream together the melted butter, brown sugar
and white sugar until well blended. Beat in the vanilla, egg, and egg
yolk until light and creamy. Mix in the sifted ingredients until just blended.
Stir in the chocolate chips by hand using a wooden spoon.
Drop cookie dough 1/4 cup at a time onto the prepared cookie sheets.
Cookies should be about 3 inches apart.