It sounds fancy, but this two-ingredient recipe is easy as can be and a great substitute for sour cream.
Combine heavy cream and buttermilk in a jar. If you use a canning jar, the measurements on the side of the jar make it easy!
Use a rubberband to secure a thin piece of cloth over the jar.
Let mixture sit at room temperature until thickened to your liking, 8-24 hours.
Stir creme fraiche and store in the refrigerator for up to two weeks.