The traditional method of making kajmak is to boil the milk slowly, then simmer it for two hours over a very low heat. After the heat source is shut off, the cream is skimmed and left to chill (and mildly ferment) for several hours or days. Kajmak has a high percentage of milk fat, typically about 60%. It has a thick, creamy consistency (not entirely compact due to milk protein fibers) and a rich taste.
Kajmak is most expensive when freshest—only a day or two old. It can keep for weeks in the fridge but becomes harder and loses some quality. It can also be matured, sometimes in dried animal skin sacks.
If left to ferment, aged kajmak has a stronger taste and is yellow in color, and is required for a pastry (pita) called gibanica.