Preheat oven to 325°. Grease cookie sheets or line with parchment paper. Sift together flour, baking soda and salt; set aside. In medium bowl, cream together melted butter, brown sugar and white sugar until well blended. Beat in vanilla, egg, and egg yolk until light and creamy. Mix in sifted ingredients until just blended. Stir in 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. Bake for 15 to 17 minutes in preheated oven, or until edges are lightly toasted. Cool on baking sheets for a few minutes before transferring to wire racks to cool completely.
If you want a big, fat, chewy cookie like the kind you see at bakeries and specialty shops, then these are the cookies for you.