Inspired by http://easybaked.net/2013/10/09/creepy-broken-glass-cupcakes/
Here are some pictures of the cookies I made this Halloween. I wanted to make cupcakes but ran out of time and energy SO I used the Pillsbury ready to bake sugar cookies I had in the fridge. I like the attached recipe since you can microwave the glass concoction vs. using your pan. I did find though that using cooking spray changed the color to more yellow glass...and the glass was kinda sticky. I tried it without but then the glass just stuck to the wax paper. Maybe next year I will try some different methods. I was able to get enough glass though to break off, so it all worked out.
Also, I don't know that I would used sweet and condensed milk again. I would probably try for something thicker. My blood isn't quite as good because I didn't have any black dye, and I was trying to use brown.