1. Butter 13x9x2-inch pan. Stir together corn syrup and brown sugar in large saucepan. Cook over medium heat, stirring constantly, until mixture comes to a boil.
2. Remove from heat. Add peanut butter chips, cocoa and butter; stir until chips are melted and mixture is smooth. (Mixture will be thick.)
3. Add cereal; stir until well coated. Immediately press into prepared pan. Cool completely. Cut into squares. About 24 treats.