Place butter in a small saucepan over low heat. Melt the butter and bring it to a gentle simmer.
Simmer the melted butter until it smells fragrant and nutty. Milk solids will sink to the bottom of the pot and foam will begin to form on the surface. Do not stir.
Once the butter smells nutty and rich, check beneath the foam layer to see if milk solids have browned (this may take as long as 90 minutes). Browning is a matter of preference; you can stop the process when the milk solids are just golden brown or leave the pot on the heat until they turn darker.
When the milk solids have browned to your liking, remove the pot from the heat and skim off all of the foam on the surface of the ghee.
Strain ghee through a few layers of cheesecloth set in a fine mesh strainer into a clean, dry jar. Cover and store at room temperature for up to three months or in the refrigerator for up to a year.