Few things are as quick and easy to make as creme fraiche. In fact, you can make this on your way out the door. All you need are two ingredients: buttermilk and heavy cream. Plus a clean jar. Creme fraiche can be spooned on fresh fruit, pies, soups or spread on biscuits and smoked salmon to name a few. French in origin, creme fraiche was traditionally the cream from cows that became sour after it was left out of refrigeration. Because unpasteurized milk is no longer the norm and our milk products are mostly ultra pasteurized, we have to add a lactic culture to make creme fraiche. We achieve that by adding buttermilk or whole milk yogurt to the cream.
The naturally occurring bacteria cultures prevent it from spoiling by making it more acidic, so you don't have to worry about it sitting out on your counter unrefrigerated as it thickens. If you don't have access to buttermilk you can use a whole milk yogurt as a substitute in the recipe below. It will have a slightly different taste
Creme Fraiche Recipe
2 tablespoons buttermilk
1 cup cold heavy cream
Add 2 tablespoons of buttermilk (or yogurt) to a cup of heavy cream, and let the mixture sit out in a clear jar in a warm place for 12 to 24 hours. (It may take as little as 12 hours if the room temperature is warm but more time for cooler rooms.) Leave it uncovered until it thickens. If you need to cover you can put a fresh dish towel over the top. After the allotted time, the mixture will thicken so that it is spoonable and become tangy in flavor. Cover it and store it in the fridge, where it will continue to mature. So easy---a five year old could make it...