This seems like the ideal opportunity to post this video:
I may not know art, but I know what I like!
I found this very detailed article about the restauration and the journalist indulge on the fact that Giuda and Jesus hands touch each other without explaining what Jesus is actually eating. It looks like a cookie to me. A traditional Italian one, I cannot recall the exact name in this moment. There is a video in English, you can enjoy it
I think it’s the other way around with haloes: They only appear, retroactively, after the fact. At the time of the Last Supper, none of the Twelve was yet a saint.
A pickle. We’re not speaking euphemistically, are we?
It’s a precursor to the beasts depicted by Maurice Sendak in Where the Wild Things Are.
Okay, to get serious, I did some searching, and it looks to me like Jesus is handing Judas a traditional Italian biscuit (cookie) called ossi dei morti, the bones of the dead.
Ossi dei morti are traditionally baked on All Souls Day.
That makes good sense in the context.
Possible reference?
Then they must have been hella stale by Passover.
Well, you know. Crunchy, like bones.
No kangaroos, and conjurer and steel band out of shot, but the roasted beastie looks like nothing so much as a yearling wombat, which is probably good as they’d be far tougher eating after that.
The ‘pickle’ is the cut end of a loaf of bread, probably belonging to the loaf and the knife seen just beside the marsupial.
I like how the main course is curled up like it’s taking a nap.
Yep, had to keep them furs coming in to make tons of money! 
People here seem to have the remarkably weird idea that paintings should be historically accurate, and that they should be taken literally. 
A painting is not a photo.
Today we are so used to photos that many people don’t even seem to know what a painting like this is. They seem to be looking at it as though it was meant to be photographically realistic.
Plautilla Nelli would be rolling her eyes, and saying,
- "These 21st century people have some pretty strange ideas! Apparently they have become too unsophisticated and primitive to understand how to look at a work of art. Do they really imagine I was trying to depict how Jesus and his disciples actually looked?
"Do they think that I think that’s what we would have seen if we had walked into the room of the Last Supper 1500 years ago?
What would be the point of a painting like that? What purpose would it serve? Are they really not capable of anything more complex than literal thinking in the future? Has the human race degenerated intellectually?"
Pautilla Nelli
If she didn’t want us to think that way, she shouldn’t have put a pickle in her painting!
Ad executive at Heinz, “Stop printing labels, it’s a freaking cookie!”
Kidding aside, this painting is stunning. 
That’s allegoric.
I wouldn’t be able to eat the body of Christ because I have gluten allegory.