Pour the heavy cream into the bowl of an electric mixer. Begin by whipping the cream on a low speed setting until it begins to slightly thicken.

Gradually increase the mixer speed to medium-high. Continue to whip for 5-7 minutes, occasionally scraping down the sides of the bowl. As you keep mixing, the cream will transition past the whipped cream stage and start to separate into butter (solid fat) and buttermilk (liquid).

Carefully remove the butter from the mixer, making sure to reserve the buttermilk for future use. Squeeze the butter thoroughly using your hands to expel any remaining moisture.

Quickly rinse the butter under very cold water to solidify it, then add salt to taste.

Place the butter in an airtight container or shape it into a log using parchment paper. Store it in the refrigerator and use it within 10-14 days.