Crème fraîche is a luxurious ingredient. It has a velvety smooth texture and a mildly sweet and tangy taste. And because it has a much more interesting flavor profile than heavy cream, I use it often in both sweet and savory dishes.
Buttermilk is often used to ferment the cream, but I prefer using kefir. It contains yeast in addition to lactobacilli, and together they create a silkier and more puddinglike crème fraîche with a richer flavor.