Place the unsalted butter in the crock pot. Set the crock pot on low and let it go for several hours. Foam will appear on top of the melted butter. After a while, the foam disappears and then reappears, turning a light golden brown. At this point, the oil is separated from the solids and can be poured through a fine strainer or cheese cloth into a sterilized glass jar. As the ghee cools, it thickens but remains quite soft with a somewhat grainy texture.

From 4 pounds of unsalted butter, I made 2 quarts of ghee.