Haven’t seen anyone mention this one, so let’s go.
The most fascinating cheese would be Casu Martzu (en.m.wikipedia.org/wiki/Casu_martzu). It is illegal to produce and consume pretty much everywhere, including in Sardinia where it is produced and was invented. It is the world most dangerous cheese, and people have died eating it.
The Wikipedia articles goes into how it is produced, but essentially you leave a good old pecorino outside with some rind removed to allow flies to put their eggs in the cheese. The larvae then consume the cheese and ferment it further. You need to eat it while the larvae are still alive, although the larvae can survive your digestive system and grow in our intestine. Traditionally you should eat the maggots, but you don’t have to.
I would never eat it, mind you, but it is definitely fascinating that such a thing exists.