1Heat oven to 375°F. Place cereal in resealable food-storage plastic bag; seal bag and crush with rolling pin or meat mallet.
2In large bowl, mix sugars, peanut butter, butter, vanilla and egg. Stir in crushed cereal. Spread in ungreased 12-inch pizza pan.
3Bake 12 minutes. Sprinkle evenly with marshmallows to within 1 inch of edge. Bake 5 minutes longer or until marshmallows are light golden brown. Sprinkle chocolate chips, peanuts and fruit snack pieces over marshmallows to look like pizza toppings. Cool completely on cooling rack. Cut into 16 wedges. Store tightly covered.