In the bowl of a food processor fitted with a blade, add the cream and process on high until the buttermilk separates from the butter. About 5 to 6 minutes. If you use a jar or hand mixer, expect this process to take longer.
Transfer the butter to a colander. You can save the buttermilk if you would like.
Squeeze the butter and get out as much of the buttermilk as possible. Rinse under cold water, turning and mashing the butter until the water runs clear.
Transfer the butter to a bowl or on to the counter and add salt. If using a different salt (like table salt) use half as much and taste as you go until your butter is salted to your taste.
Transfer the butter to an air tight container for up to one month.