I haven't made creme fraiche for years, but was reminded of it today. It is made of cream with high fat content (but no thickeners etc), and a starter - yoghurt or buttermilk, even sour cream might work. Kept at a temp of around 25C for 24-48 hours or 40C for around 8 hours ferments it nicely into creme fraiche. Very delicious.
I was also reminded that the best ghee is made from "cultured cream" which is what creme fraiche is. You take the creme fraiche and make butter out of it, then take the cultured butter and make ghee out of it. I have never done it, but I should.
Here is how to make cultured butter from cream (then take the resulting butter and make ghee).
https://www.pantrymama.com/cultured-butter/
and this is another good one
https://www.abeautifulplate.com/how-to-make-cultured-butter/