To make butter, pour 2 cups of heavy cream into a large bowl, and beat it with an electric mixer for approximately 10 minutes, until it begins separating, then strain off excess liquid, and season it with salt. Press the butter into a bowl and again pour off any remaining liquid, then refrigerate.
Another way to make butter is to pour 1 gallon of fresh, non-homogenized milk into a clean container and refrigerate it for 12 hours. Skim the cream off the top with a spoon, and stop when the liquid on the spoon is watery milk instead of cream. Next, let the cream sit at room temperature for another 12 hours. This process ripens the cream and gives it a buttery flavor. Pour the cream into a large jar until it is 1/3 full, and shake it vigorously until the cream begins to thicken and the buttermilk separates from the butter. This process takes up to 30 minutes.
When the butter starts to separate from the buttermilk, shake it with less force. When the mass of butter turns yellow and becomes firm, strain it through a colander. Save the buttermilk if desired. Thoroughly rinse the butter in very cold water, and place it in a bowl. Work any excess liquid out of the butter by pressing and squeezing against the sides of the bowl with clean fingers or the back of a spoon. Salt the butter to taste, and store it in the refrigerator along with the buttermilk.