With the accents, it's crème fraîche, pronounced krehm fresh.
I prefer the method of adding a little live-culture yogurt to heavy cream, then letting it sit out at room temp until it tastes and feels right (thickened and slightly tangy). If you can find heavy cream that hasn't been ultrapasteurized (good luck!

), that works best. And no, there is no health risk to leaving the stuff out of the fridge while the cultures are working!
Vermont Butter & Cheese makes a good version. As Breton Beats says, it's fairly expensive, but it's reliable and delicious.