PREHEAT oven to 250°F. Microwave peanut butter and margarine in large microwavable bowl on HIGH 1 minute or until melted. Add marshmallows; toss to coat. Microwave 1 minute or until marshmallows are puffed.
STIR in remaining ingredients. Pour evenly into 2 greased 13x9-inch baking pans.
BAKE 10 minutes. Cool completely. Break into small pieces. Store in airtight container at room temperature.