Cheese

Cheese!

A (delicious) substance made from sour milk and mold and time, cured with various other things and stored in cool dry areas, occasionally sealed in wax or another non-porous substance to keep moisture out/in.

Varies greatly by region, of course, but originated with humans (I think, maybe halflings, need to ask Cat), and they remain the best at it. Elves remain jealous and pretend theirs is better, and they're a bunch of damn liars.

Also originally made with goats' milk, as those were some of the first domesticated milk animals. (Elves actually don't steal milk directly from the beasts. I can't remember if there's a rule about this, I think it blights them or something.), and developed before seafarers reached their landmass and started spreading it.

Humans are the first makers of cheese, but as they've traveled, other cultures have learned to imitate and make their own. Many more milk beasts as domesticated by humans and halflings helped develop the technique.