In ungreased 8-inch round cake pan, spread cereal evenly. Drop ice cream by small spoonfuls on top of cereal. Rinse metal spoon with hot water; wipe dry. With back of hot spoon, spread ice cream evenly in pan, pressing down firmly and reheating spoon as needed.
In small microwavable bowl, mix fudge topping and peanut butter until well blended. Microwave on High 20 seconds. Stir to blend; continue to microwave on High in 5-second increments until mixture can be stirred smooth and is pourable.
Pour topping mixture into small resealable food-storage plastic bag; seal bag. Cut small hole in bottom corner of bag. Drizzle mixture over ice cream. Freeze until firm, at least 2 hours. Cut into wedges to serve. Reheat and serve any remaining topping with pie.