Bake cupcakes according to the instructions on the box mix. (I made 10 cupcakes instead of 12 to make larger ones and baked them in black cupcake liners) Let cool completely before decorating.
Spread out the purple cupcake liners and place the baked cupcake inside of them for an extra pop of color!
Once no longer warm, you can begin to ice the cupcakes! Add the Cherrybrook Kitchen icing to a plastic bag and snip off the corner. Squish all the icing to the snipped corner and begin to pipe the icing onto each cupcake in a swirly motion.
After the cupcakes are iced, prepare your monster eyes by mixing confectioner sugar and water in a small bowl. You want the consistency to be not too thick and not too runny (however you can't go wrong). Add about 3 drops of green food coloring (enough to be a bright green) and mix until the coloring is evenly distributed.
Dip the mini marshmallows half way into your mixed icing and stick them into the frosted cupcake tops, green side up. Stick one of the candy eyeballs on top of each mini marshmallow, the green icing acting as a glue.