Gjetost (occasionally referred to as Gudbrandsdalsost, and spelled gjeitost in Norwegian**) is a Norwegian cheese that originated in the Gudbrand valley. The name of the cheese is derived from the Norwegian word for goat ("gjet"). It is a rich brown color, with a smooth, but non-shiny surface. It's fat content typically varies between about 30 and 45%, with a semi-hard texture. It is typically sold in blocks. "Ski Queen" is one brand name that is relatively easy to find in the United States.
This cheese was traditionally made entirely from goat's milk, but most of the gjetost produced today is made from a combination of goat's milk, cow's milk, and the whey from cow's milk. Regardless of what combination of milk products is used, the milk is boiled until the lactose caramelizes*, at which point it is poured into molds and cooled. This caramelization process gives the cheese its characteristic color, and also imparts a sweet flavor, owing mainly to the change in sugar content of the cheese (ounce for ounce, gjetost generally has about ten times the digestible carbohydrates of other cheeses).
While it is generally considered a breakfast cheese, the aforementioned sweet flavor makes it well-suited to desserts. It should be shaved off in thin slices, and is variously recommended alongside coffee, fruit cake, and in combination with fruit in eggs.
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I think it is safe to say that gjetost is the strangest tasting cheese I have ever encountered. It is kind of sour in the way that sour cream is sour, and sweet from the caramelized milk sugars, with the added oddity of that peculiar gamey flavor that all goat's milk cheeses share. If you don't like goat cheese (shame on you!), it is very likely that you won't enjoy this cheese. Do not be deceived; despite its sweetness, it is decidedly goaty.
Then there is the whole texture issue. Just about every information source I encountered describes this as "a semi-hard cheese." This is entirely meaningless. The texture is sort of a cross between the texture of cheddar and the texture of peanut butter. In your hand it is, perhaps, a bit softer than cheddar, but with a similar sort of elasticity. In your mouth, however, it rapidly and thoroughly adheres to the roof of your mouth, inspiring the kind of tonguing usually reserved for mouth sores and jolly ranchers that have become stuck to teeth. The stickiness of the cheese is in direct proportion to the surface area to volume ratio of the piece of cheese consumed, so eat with caution.
Personally, I find the whole gjetost experience very odd. I am not entirely convinced that I actually like it (for goodness sake, it's a cheese that goes well with coffee! Clearly it shouldn't be trusted!!), but I keep eating it anyway. It's nice, actually; it serves as appropriate punctuation to the strangeness of everything else in this universe.
the Ski Queen Gjetost box labeling
**Thanks for this tidbit, Nordicfrost!
*And, on a side note, I can't help but wonder whether this cheese would be relatively easy on lactose intolerant folks, owing to the fact that the lactose is broken down during the caramelization process. I couldn't find any information about this from any of the sources I checked, and I just couldn't bring myself to experiment on my friends, so, for the moment, this remains a wholly untested hypothesis. Goat!