Spray cookie sheet with Pam. Line cookie sheet with whole saltine crackers. Cover entire sheet. Cook butter, margarine and sugar over medium heat. Boil for 5 minutes, stirring constantly. Pour mixture over crackers and bake at 350 degrees for approximately 8 minutes until mixture bubbles. Remove from oven and pour chocolate morsels over the entire mixture. After a couple of minutes the chocolate will melt. Spread evenly. Top with nuts. Place in freezer for 15 minutes. Break into bite size pieces.