Pavenders?! I did a search and it turned up some ideas for preparing something that could be described as pavenders. But it brought up an interesting list from "The Silver Chair". I am not sure from where, but methinks it is from either the beginning of the book when Jill and Eustace were at Cair Paravel. Or (less likely) in the giant's castle, although some of these foods would have to come from giant animals --"So first of all he has porridge and pavenders and kidneys and bacon and omelettes and cold ham and toast and marmalade, and coffee and beer." There are some ideas there. One I would not shun is kidneys. I have read of at least two English preparations for lamb kidneys, both a traditional Edwardian breakfast food. Both descriptions indicated that they were so good that the people involved wanted more. I have never tried this myself, although I should.
Another inspiration source, also from :The Silver Chair" (and my first thought on the subject) is some of the things that Puddleglum prepared for Eustace and Jill. One that comes to mind was eels. Not necessarily a festive food (which it sounds like lamb kidneys could be) but something of English roots and definitely Narnian.