Place butter in a small stainless-steel saucepan over medium-high heat. Once the butter melts, it will start to foam. Reduce the heat to medium and skim the foam from the top. Cook until the milk solids drop to the bottom of the pan and turn golden brown (gently tilt the pan so you can take a peek). The ghee will bubble vigorously at first and quiet down when it’s nearly done. Depending on the type of butter you use (some brands have higher water content than others), the dimensions of your pan, how much heat your stove kicks off, and whether you use more or less butter than called for here (which is fine), this process can take 10-20 minutes. But instead of setting a timer, keep an eye on what’s happening in the pan.
Strain the ghee through a cheesecloth-lined fine-mesh strainer into a clean 1-pint jar. Cool and cover tightly. Store in cool, dry cupboard for up to 3 months or refrigerate indefinitely.