1/2 c. butter
1/2 c. packed brown sugar
1 c. flour
1/2 c. graham cracker crumbs
2 c. miniature marshmallows
1 (6 oz.) pkg. semi-sweet chocolate pieces
1/2 c. chopped walnuts (optional)

Preheat oven to 375 degrees. Beat butter and brown sugar until light and fluffy. Add combined flour and crumbs; mix well. Press onto bottom of greased 9-inch square pan. Sprinkle with remaining ingredients. Bake at 375 degrees for 15-20 minutes or until golden brown. Cool; cut into bars.