Coat 13 x 9 x 2-inch microwave-safe dish with cooking spray. Arrange Keebler(R) Grahams Original crackers in single layer in dish, breaking crackers as needed to fit. Sprinkle marshmallows evenly over crackers.
Microwave on HIGH 1 minute or until marshmallows are puffy. Remove from microwave. Cool completely.
In 2-quart microwave-safe mixing bowl combine chocolate morsels, corn syrup and butter. Microwave on HIGH about 1 1/2 minutes or until chocolate is melted, stirring every 30 seconds. Stir in peanut butter. Add Kellogg's(R) Rice Krispies(R) cereal, mixing until combined.
Spread evenly over marshmallows. Cover and refrigerate about 1 hour or until firm. Cut and store in airtight container in refrigerator.
