Head cheese is popular throughout Europe. Just to clear things up before we move any further: it does not actually contain any cheese. Head cheese belongs to a family of dishes where prime quality meats from the head of a pig or calf (seafood, lamb, and poultry can also be used) are preserved into a jelly, known as aspic, made from cooled stock that's been turned into gelatin.
As with so many other dishes in Europe, its origins can be traced back to the Middle Ages and was primarily "invented" as a food preservation method. Sülze is a cold cut (if heated the jelly will melt) that's seldom served as a main course; nowadays it's more popular as a lunchtime dish, and one of my favorites at that.
Spreewälder Gurkensülze, Holsteiner Prinzensülze or Bauernsülze are typical sülze varieties in Germany, found at good butchers and supermarkets alike.
In Scandinavia, head cheese is known as sylte and often served at Christmas lunches. In France it's called fromage de tête. Italians know it as formaggio di testa, while the Dutch call it preskop (literally meaning pressed head). Many Asian cuisines have strong traditions for preserving food in cooled meat broth too.
I prefer to eat my sülze sliced on full-grained dark rye bread with a crispy crust, coated with butter or duck fat with a swipe of mustard, half a hard-boiled egg and chilled beetroot pickles.
Needless to say, sülze should always be accompanied with a good quality beer, I recommend a delicious German crystal wheat beer (Kristallweizen).