Creme Fraiche is a slightly fermented double cream and has a slightly sour taste. It pairs very well with fresh fruit deserts and pancakes. it is often called for in sauces and soups and even meat dishes like Hungarian Goulash and Beef Stroganoff .
It is not always available in North America and can be quite expensive.
It is not that difficult to make though. Heat (do not boil) some heavy whipping cream and add some buttermilk. Leave it covered in a slightly warmed place overnight (+-24hours). It is ready when it looks like thick spooning cream. If it is still runny after 24 hours move it to a warmer place and leave it there for a few more hours until it is thick.

