Preheat oven to 325 degrees F. Grease a 13"x9" baking dish and set aside.
Mix together the melted butter and sugars in a large bowl. Add the egg, egg yolk, and vanilla and mix well. Fold in the flour, salt, and baking soda just until combined. Fold in the chocolate chips. Pour batter evenly into the prepared dish.
Bake at 325 degrees F for about 24-28 minutes, until bars are light golden brown, slightly firm to the touch, and edges start pulling away from sides of pan. Cool to room temperature before cutting into squares.