Grease a 9x13 inch pan with butter or line it with parchment paper for easy removal of treats.
In a large saucepan over low heat, melt 3 tablespoons of unsalted butter.
Add the entire package (10 oz) of mini marshmallows to the melted butter and stir continuously until completely melted and smooth.
Remove the pan from heat and quickly stir in green food coloring a few drops at a time until desired green shade is reached.
Immediately add 6 cups of Rice Krispies cereal to the marshmallow mixture and stir gently but thoroughly until every piece is coated.
Transfer the mixture into the prepared pan and press evenly using a buttered spatula or wax paper. Let cool for about 30 minutes or until firm.
Once cooled, cut into rectangles or squares resembling Frankenstein’s head.
Use black food coloring to add stitches or hair details.
Attach candy eyes using a dab of melted chocolate.
Use chocolate chips or melted chocolate for the mouth, bolts, and other fun monster details.
