Pour heavy cream into a food processor, stand mixer, or blender. Process on high until butter separates. The time to separation will depend on the equipment and the speed you use (anywhere from 3 to 10 minutes). Pay attention and stop processing once the liquid has separated from the solids.

Transfer solid butter pieces to cheesecloth and squeeze out as much buttermilk as possible; reserve buttermilk for another use. Scrape butter out of cheesecloth and run under cold water, squeezing out excess liquid, until water runs clear.

Return butter to food processor; add remaining ingredients and blend well. Use a butter mold to shape, if desired, or store in any airtight container. Keep butter refrigerated for up to 3 weeks; frozen, it will last several months.

The buttermilk you’ll have after making butter is thin and slightly sweet. You shouldn’t bake with it, but it is excellent for adding to stews, braises, and smoothies. Store buttermilk in the refrigerator and use within 1 week.