Creme Fraiche - French "Sour Cream"

Many recipes call for creme fraiche, a thick, tangy cream similar to sour cream, but smoother and thicker. In France they make it with unpasturized cream, but in the United States we have to improvise by using the natural fermenting agents in buttermilk. Creme Fraiche is great for cooking because of its' rich flavor and stability - it doesn't break down when heated, unlike sour cream.
This recipe is from "Cuisine At Home" magazine.