Step 1

Heat oven to 350°F. Spray 13x9-inch pan with cooking spray. In large bowl, mix butter, brown sugar, vanilla and egg yolk. Stir in flour and salt. Press in pan.

Step 2

Bake 25 to 30 minutes or until very light brown (crust will be soft). Immediately sprinkle chocolate chips on hot crust. Let stand about 5 minutes or until chocolate is soft; spread evenly. Sprinkle with nuts.

Step 3

Cool 30 minutes in pan on cooling rack. For bars, cut into 8 rows by 4 rows.