1. Fill and preheat the SousVide Supreme water bath to 95F /35C.
2. Combine the cream and buttermilk in a sterilized pint Mason jar and seal with a lid. There is no need to heat the mixture.
3. Immerse the jar in the water bath and cook 8 to 12 hours.
4. Remove the jar from the water oven and quick-chill submerged in an ice water bath (half ice and half water) to rapidly reduce the temperature.
5. Refrigerate, tightly sealed, up to 3 weeks.
Courtesy of Pam McKinstry SVKitchen.com