1. Line 8-inch square pan with foil, leaving 2-inch overhang on 2 sides. Generously grease or spray with nonstick cooking spray.
2. Melt marshmallows and butter in medium saucepan over medium heat 3 minutes or until melted and smooth, stirring constantly. Remove from heat.
3. Add cereal; stir until completely coated. Spread in prepared pan; press evenly onto bottom using rubber spatula. Let cool 10 minutes. Using foil overhangs as handles, remove treats from pan. Cut into 16 bars. Press candy decorations onto top of treats.