Heat butter in a medium saucepan over medium-low heat. Skim off any foam that comes to the surface. The milk solids will settle to the bottom of the pan and the butter will become clear and bubbly. Continue cooking, without stirring, until the solids at the bottom begin to brown and the butter darkens slightly, 15 to 25 minutes (tilt the pan so that you can see the color of the solids). Pour the butter through cheesecloth or a coffee filter set inside a fine-mesh strainer. You may need to coax the butter through the cheesecloth with a rubber spatula. Store, covered, in the refrigerator or at room temperature.Advertisement
To make ahead: Store at room temperature for up to a month or refrigerate for up to 3 months.