How do you make creme fraiche

I find that you can also use a nice, cultured yogurt instead of buttermilk. Many people don't want to commit to a half gallon of buttermilk, but a spoonful of yogurt will work just as well. The basic cultures in buttermilk are the same as in yogurt, with some minor variations.

Or shake a tablespoon of buttermilk and a cup of heavy cream together in a *clean* glass jar. Allow the mixture to sit at RT for 12-24 hours then refrigerate. It will keep for about 2 weeks, becoming tangier as it ages.

It's very easy, and so much less expensive than buying it. Here's how I make it:
http://wp.me/p27pPl-il