LINE 9x9-inch square baking pan with foil, extending over edges of pan.
MICROWAVE butter and marshmallows in large microwave-safe bowl on HIGH 1 1/2 minutes. Add cereal; stir until evenly coated.
DIVIDE cereal mixture into two separate bowls. Stir peanut butter in one half and jam into other half until smooth. Press peanut butter layer into prepared pan. Press jam layer on top of peanut butter layer. Chill 10 minutes.