What's was your favourite fast food product that unfortunately got retired and never came back?
Here, for a while at McDonald's there was a 🍔 called "the 1955" and it was the best, big pieces of onion, an special sauce, buns and big piece of beef with bacon (for Europe standards anyways) it disappeared once and came back for an encore only to be removed again and never return.
Taco Bell's Volcano Taco. They brought it back for like a month and took it away again. Technically it's still available in Kuwait but I can't get anyone to mail me a bag of the sauce.