Place the marshmallows in a large heat-proof microwave-safe bowl. Add the butter cubes on top. Place in the microwave and cook for 1:30 to 2 minutes, or until the marshmallows puff up. Remove the mixture from the microwave and whisk until the butter is incorporated. Add the green food color and salt. Whisk until well combined. (This can also be done in a saucepan on the stove top.)
Place popped popcorn in an oversized mixing bowl. Pour the melted marshmallow mixture on top and stir together with a wooden spoon. This will be messy, and you won’t be able to coat every piece of popcorn, but do the best you can.
Spray your hands with baking spray or butter them. Shape the mixture into 8 apple-sized balls and place on a piece of parchment paper. Re-spray or butter hands as needed. Refrigerate popcorn balls until firm.
Use a knife to cut a slit in one side of a popcorn ball. Insert plastic vampire teeth and shape the popcorn ball around it. If the vampire teeth are too springy they will cause the popcorn ball to split in half. If you experience this, reshape the ball and cut the teeth at the hinges with scissors; insert the teeth as two separate pieces (I had to do this with 2 of my monsters). Repeat with remaining popcorn balls.
Add candy eyeballs above the mouth. They should adhere to the sticky popcorn balls, but if they don’t then use frosting or melted chocolate as adhesive.
Cut dried papaya in half lengthwise to make tongues. Place the slices inside the monster mouths.
Package monster popcorn balls individually in clear cellophane bags or stack them on a cake plate to serve.
Keyword mini marshmallows, moss green food color, popcorn