MELT chocolate in microwaveable bowl on MEDIUM 1 min., stirring after 30 sec. Stir until chocolate is completely melted. Use clean small paintbrush to paint a ghost face on inside of each of four (1-cup/250-mL) clear plastic cups with the melted chocolate. Refrigerate until ready to use.
PLACE milk and dry pudding mix in blender; cover. Blend 1 min. or until smooth.
POUR into prepared glasses; top with the whipped topping. Serve immediately. (Mixture thickens as it stands.)