Spray a 9×9 pan lightly with cooking spray; set aside.
Melt butter over low heat in large saucepan on stove. When butter is melted, stir in one bag of mini marshmallows until melted.
Remove from heat and stir in 6 cups of Pebbles cereal.
Press evenly into the prepared pan. Let cool completely.
Use a ghost-shaped cookie cutter to cut the treats into shapes.
Melt the white candy coating over a double boiler, or according to package directions, and stir until the candy is melted. Using a spoon, stir the chocolate until smooth.
To coat the ghosts, place one ghost onto the center of a large fork.
Hold the ghost over the bowl of melted candy coating, and using a small ladle, spoon the melted candy coating evenly over the top of the ghost allowing the excess chocolate to drip back into the bowl.
Once the excess chocolate has stopped dripping, transfer the ghost to a sheet of waxed paper and gently slide him off the fork. Allow to cool completely.
Using the black edible ink marker, draw spooky eyes and mouths on each treat.
Insert one lollipop stick into the bottom of each ghost treat.