1 pound of unsalted "European-style" (high butterfat content) butter
Over medium-low heat in a saucepan, melt butter and slowly cook until the butter sticks to the bottom of the pot. The butter will foam at the top during the process but will eventually cook out the milk solids. Do not brown the butter - although a slight amount will be fine.
Strain through a cheesecloth-lined fine mesh strainer into a glass jar. Keep in the refrigerator or on the counter and use like oil or butter for cooking.
Alternatively, you can cook it even longer and brown the milk solids and then strain - leaving you with ghee.