chocolate cookie frostingor other frosting to pipe monster's face
Squirt a dollop of green gel food coloring onto a paper towel, and dipthe top of the marshmallows in it. Twirl it around the top edges to give the monster man some hair. Then, dot off the excess on the clean parts of the paper towels.
Pipe on 2 dots for the eyes & a straight line for the mouth on the marshmallow. Top each cupcake with one monster marshmallow.