- 2 cups heavy cream
- 2 tablespoons buttermilk
- Combine the cream and buttermilk in a clean glass jar. Place the uncovered jar in a saucepan of barely simmering water. When the cream is just warm, remove it and cover tightly with plastic wrap or wax paper, using a rubber band to secure the wrap. Put the jar in a warm place, avoiding drafts.
- Once thickened, after 12 to 24 hours, stir once, re-cover, and place in the refrigerator, where it will thicken even further and keep for about 2 weeks.