I believe this quest uses player crafted muffins only, not vendor bought ones (there seems to be 2 different items with the same name).
Anyway, I went on live and think I found every vendor that still accepts the full muffin crate. All the new ones I found, I put in the comments section on the
allakhazam page.
I checked every vendor that sells muffins in the AK database (was only 1 grobb vendor missing from live to try, the rest were all still in-game), and tried handing the crate to every one of them.
Each of these vendors will probably accept the "bag of bread loaves" as well, but it's a rare drop in runnyeye on live now, so it'll take a while to gather all the info for that quest also. I did add 2 for that quest so far.