1Heat oven to 350°F (325°F for dark or nonstick pan). Grease and flour bottom and sides of 15x10x1-inch pan, or spray with baking spray with flour.
2In large bowl, mix cake mix, oil, water and eggs with spoon. Stir in raisins and nuts. Spread evenly in pan with metal icing spatula or dinner knife.
3Bake 20 to 24 minutes or until bars spring back when touched lightly in center. Cool completely, about 1 hour. Spread with frosting. For bars, cut into 8 rows by 6 rows. Store loosely covered.