Rocky Road Bars

From Betty Crocker Magic From A Mix

1 pkg Betty Crocker SuperMoist milk chocolate cake mix
1/2 C margarine or butter, melted
1/3 C water
1/4 C packed brown sugar
2 eggs
1 C chopped nuts
3 C miniature marshmallows
1/3 C Betty Crocker Rich & Creamy chocolate ready-to-spread frosting

Heat oven to 350. Grease 13x9x2" pan.
Stir together half of the dry cake mix, the margarine, water, brown sugar and eggs in large bowl until smooth. Stir in remaining cake mix and the nuts. Spread in pan. Bake 20 minutes; sprinkle with marshmallows.
Bake 10-15 minutes or until marshmallows are puffed and golden. Microwave frosting in microwavable bowl uncovered on high 15 seconds. Drizzle over bars. Cool completely. For easier cutting, use plastic knife dipped in hot water. Cut into 6 rows by 4 rows.