I too want to make my own yogurt! Currently I had a half gallon of heavy cream in the fridge for only a week and I noticed it becoming thick and clotted (but not bitter, only a little like cream cheese in ‘butteriness’ taste) and quite like yogurt in taste! We eat a lot of purchaced yogurt and I can only guess that some culture found its way into lacto heaven. This is the best yogurt I’ve had ever had! Very rich and not very tangy. Kinda like a double rich version of Trader Joe’s French Style Whole Milk yogurt. I’m hoping I can replicate what happened but I’m only half way through the carton.