1 cup heavy cream (pasteurized, not ultra‑pasteurized)
2 tablespoons cultured buttermilk
- Combine cream and buttermilk in a glass container.
- Cover and let stand at room temperature (about 70°F) from 8 to 24 hours, or until it becomes very thick.
- Stir well and refrigerate, covered, for at least 24 hours before using. Will keep up to 10 days in the refrigerator.