MICROWAVE peanut butter in large microwaveable bowl on HIGH 1 min. or until melted. Add marshmallows; toss to coat. Microwave 1-1/2 min. or until marshmallows are completely melted and mixture is well blended, stirring after 45 sec. Add cereal; mix well.
PRESS half the cereal mixture onto bottom of 8-inch square pan; spread top with jam. Cover with remaining cereal mixture, pressing firmly into pan to secure.
COOL completely before cutting into squares.