Heat unsalted butter in a stainless steel, thick-bottomed sauce pan, over a low-medium flame.
Allow the oil (ghee) to separate from the milk solids.
Periodically remove the foam that accumulates at the top.
When the oil is clear in color, the ghee is done.
Remove from the stove and allow to cool for a while, than carefully pour off the ghee into a wide-mouthed jar through several layers of cheese cloth secured to the opening of the jar or through a fine mesh strainer.