3/4 cup unsalted butter, melted
1 cup packed brown sugar
1/2 cup white sugar
1 egg yolk
1 TBSP vanilla extract
1/2 teaspoon baking soda
1/2 teaspoon salt
1 cup all-purpose flour
1 cup whole wheat flour
2 cups semisweet chocolate chips
Grease cookie sheets or line with parchment paper (I actually did neither, and they came out fine on a plain old bare shiny metal cookie sheet). 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 dry ingredients until just blended. Stir in the chocolate chips, then chill in the fridge for 1-2 hours.
Drop cookie dough 1/4 cup at a time onto the prepared cookie sheets (I did large golf ball size chunks, and could fit 9 at a time - they spread quite a bit, so don't try to cram them). Cookies should be about 3 inches apart. Bake for 12 to 15 minutes in a 325 F preheated oven, or until the edges are lightly toasted. Cool on baking sheets for a few minutes before transferring to wire racks to cool completely. For a softer cookie be careful not to overcook- remove cookies from oven when the edges are barely toasted. For a crunchier cookie, bake for 15-17 minutes or until edges are golden brown. Makes 14-17 cookies.