Line a 15x10x1-inch pan with waxed paper. Grease the waxed paper.
Combine marshmallows, butter, and peanut butter together in a large microwave-safe bowl. Cover bowl and heat mixture in the microwave until marshmallows are melted, about 2 minutes. Stir well.
Stir rice cereal into marshmallow mixture until well coated; spread onto the prepared pan.
Combine chocolate chips and butterscotch chips in a microwave-safe bowl. Heat mixture in microwave until melted, about 2 minutes. Stir well.
Spread chocolate mixture over rice cereal mixture, leaving a 1-inch border around edges. Roll rice cereal mixture around chocolate filling, jelly-roll style and starting with the short side. Peel waxed paper away while rolling. Place roll, seam-side down, on a serving platter. Refrigerate until set, about 1 hour. Cut into narrow slices.
