In a phrase, it's meat jello. Mmm, right?
As evidenced by the photo above, head cheese is not a cheese at all, but rather a cold cut made of all the parts of an animal (cow, pig) that you don't normally want to eat, suspended in aspic (or jelly, traditionally made by boiling the head of an animal, brains/eyes removed, to produce a stock that would contain natural gelatin from the skull), and sliced. A peasant food, no doubt. It might also include feet, tongue, and heart, and is usually flavored with onion, peppercorns, allspice, bay leaf, salt and vinegar.
I first encountered head cheese at Safeway of all places, right there next to the braunschweiger and salami. I was horrified, and I'm not only relatively fearless meat eater, but also Chinese. And you know what they say about Chinese - we'll eat anything on four legs that isn't a table, and anything on two legs that isn't a plane. But this head cheese was really something else. And with a name like 'head cheese,' which sounds like a euphemism for 'brains,' it didn't exactly encourage me to try it.
Then I realized that I have probably already eaten a variation on head cheese, in the form of cold cuts in Vietnamese banh mi sandwiches. Along with "pork roll," which is also pretty much all the parts of the animal you don't normally want to eat, ground up and pressed into cold cut format. And then I thought, well, how is head cheese any more disgusting than, say, a hot dog or a chicken nugget? Just because you can actually still see what the meat product is made of since it hasn't been processed beyond all recognition?
The answer, of course, is that head cheese is NOT more disgusting. In fact, it is less processed and thus 'safer' in that you sort of know what's going into it. As opposed to the hot dog or chicken nugget, which contains heaven-knows-what including bones, beaks, eyeballs, membranes of all sorts. Blech. I think i just threw up a little bit in my mouth.