I first saw the Frankenstein cupcake idea in a magazine, but couldn't find it when the time came. I ended up peeking at a few pic of similar ideas on Flickr and decided to just wing it as I have done ice cream cone cupcakes in the past.
Here's what you need:
Package of ice cream cones- Tip--buy more than you need because some will likely be damaged!
Box cake mix- I used an orange and fudge mix special for Halloween
Ingredients called for on box- Usually water, vegetable oil, and eggs
Container of chocolate icing
Full size peanut butter cups
Black decorator's icing- I used Wilton's black icing in a tube that the tip is "supposed" to fit on!
A mini muffin pan
Step 1: Place 6 (or 12 if you have a big mini muffin pan) cones into your pan. Fill with prepared cake mix to just above where the cone widens.
My box called for the oven to be at 350 degrees and I found through trial and error that 15 minutes seemed to be the perfect baking time for my cupcakes. Your time may vary a bit, but you can always check by poking with a toothpick. If it comes out clean, it's done!
Step 2: Place peanut butter cup on top when the come out of the oven immediately. They will melt a bit to stick onto the cupcake top.
Step 3: Decorate! Put chocolate icing around edges of peanut butter cups (or any other color you like). Push 2 candy corn in for the neck plugs (I guess that's what they are!) Draw a face with your choice of icing. Black was quick and easy for my purposes. If you don't have tips and bags for decorating, you can put your icing in a sandwich bag and cut a small corner off with kitchen scissors.
A few tips I discovered along the way. Don't make the night before because my candy corn got sticky and started to melt and fall out due to the moisture in the cake mix. Also, the fine detail in the icing decoration started to run. I would bake the cupcakes and do the basic icing the day before and decorate only a few hours prior to your party so they are looking their scariest!