The first thing you have to do is make all your monsters. The fudge comes together so quickly and sets up fast, so these need to all be done and ready first!
They're super easy to make- put your colored sugar into 3 separate bowls. You don't need a ton- just cover the bottom of a small bowl like I have pictured. Next, take a pair of kitchen shears and cut your large marshmallows into 3 rounds. Two of the rounds will have 1 sticky side, the middle one has 2 sticky sides. Put your eyeballs on one of the sides- I did some cyclops monsters with 1 eye, others had 2. I think it would have been fun to make a few with 3 eyes! Now you're going to stick your monster face down in the colored sugar, face side down, so that it coats around the eyes. The middle piece with 2 stick sides can be coated on both sides so it's easier to handle. Set the colored monsters aside once finished and repeat until you've got 30 monsters.
To make the fudge: Open your can of sweetened condensed milk and pour into a medium sized glass bowl. Microwave for 1 minute, stir, then microwave for an additional 30 seconds to 1 minute, until milk begins to bubble. Add the semi sweet chocolate chips and the butterscotch chips to the bowl. Stir gently then let sit for about 30 seconds, so that the chocolate has time to heat up and melt. Add in the vanilla and stir until smooth. Just before you pour into the pan, add in 1 cup of mini marshmallows* and stir quickly, just until they're incorporated. Pour into a greased 8x8 square pan.
Immediately begin setting the monsters onto the fudge, gently pressing them in about half way. You should be able to cover the entire surface, using 25-30 monsters, depending on how close you set them. I put mine very close together and I fit all 30 monsters.
Refrigerate for about 30 minutes, or until fudge has cooled completely and hardened. Cut into small squares and enjoy!
*I ran out of mini marshmallows so I cut up 2 of those gigantic roaster marshmallows. It worked but trust me, cutting one up wasn't fun! (hello, sticky mess!) Do yourself a favor and have mini marshmallows on hand!