Mysost is a Norwegian cheese made from caramelized cow's milk whey, often the whey left over after making traditional curd cheese. When made with goat's whey, the cheese is called gjetost. They are unusual--not what you'd necessarily expect when someone tells you they are serving you cheese. Both cheeses are smooth, sweet, sour, salty, slightly brown--and deliciously different.
The recipe calls for only two ingredients. We purchased a couple of quarts of whey from our dairy farmer, combined it with a little cream, and put it on to heat. (If you prefer, you can make it with only whey, although your cheese will be slightly grainier.) You can certainly use your own whey--that made after draining yogurt to make yogurt cheese will even work. I don't think it is particularly easy to find commercial whey, however.
We brought the whey up to a full boil then turned down the heat a bit. After several hours (4 for us, but sometimes as much as 12 hours) at a gentle boil, the whey had reduced to a fudge-like consistency. After beating it severely, we cooled it in its pan over a bowl of iced water and poured it into a little buttered glass bowl.
Mellowing in the refrigerator for 24 hours helps the flavor of mysost. But I couldn't wait:
Excellent instructions can be found in Ricki Carroll's Home Cheese Making.