1 cup whipping cream, room temperature
1 tablespoon buttermilk or 1/2 cup sour cream, room temperature
In a jar with a lid, place whipping cream and buttermilk or sour cream; cover securely and shake 15 seconds. Set aside at room temperature for 24 hours or until very thick. Stir once or twice during that time. Cream will thicken faster if the room is warm.
Stir thickened creme fraiche well. Refrigerate at least 6 hours before serving. Cover tightly and store in refrigerator for up to 2 weeks.
Whipped Creme Fraiche: Beat creme fraiche until soft peaks form (it won’t become stiff).
Sweetened Creme Fraiche: Add 1 to 2 tablespoons powdered (confectioners) sugar before shaking the cream.
Vanilla-flavored Creme Fraiche: Stir 1 to 1 1/2 teaspoons vanilla extract into creme fraiche just before refrigerating.