Lightly spray 15x10x1-inch pan with cooking spray. In large microwavable bowl, microwave marshmallows and butter uncovered on High 2 minutes. Stir with wooden spoon until smooth. Add cereal; stir until completely coated. Stir in 1 cup chocolate chips. Quickly spoon mixture into pan, pressing gently. Let stand 30 minutes. Using greased 4 1/2-inch ghost-shaped cookie cutter, cut out 9 ghosts.
In medium microwavable bowl, microwave candy coating uncovered on Medium (50%) 1 minute 30 seconds, stirring once, until melted. Dip top of each ghost cutout lengthwise in melted candy. Place on waxed paper. Attach 2 chocolate chips, point side down, on each ghost for eyes. Let stand until set, about 30 minutes.