In a microwave-safe mixing bowl combine the butter and mini marshmallows.

Place in your microwave and cook for one minute. Stir the mixture and place back in the microwave and cook for an additional minute if marshmallows are not melted. After cooking time is done, stir until marshmallows are melted.

Add the vanilla extract and green food coloring to melted marshmallows and stir until combined.

Add the Rice Krispies to the marshmallow mixture and stir until combined. Cool for about 5 minutes.

While mixture is cooling line a sheet pan with parchment paper. Spray a 1/3 cup measuring cup with nonstick spray then scoop the Rice Krispie mixture into the cup and place on lined sheet pan.

Lightly grease your hands and gently roll mixture into rounded shapes. Place back down on line sheet pan.

Press a few eyes into the monster's head and allow to cool at room temperature for one hour.

Store in an airtight container for up to three days.