Please, please, don't go the way of other "Renaissance" festivals by serving modern food with "Ye Olde" names. There are plenty of yummy treats which are appropriate to the time and place.
OK, maybe I have an axe to grind. Once upon a time, I was at the Renaissance Pleasure Faire in Agoura, California, a paying customer in a pretty good costume. I was approached by two women in better costumes who had a lot of unsolicited criticism of the shape of my hat and the trim on my skirt. All this in front of the Beef Teriyaki on a Stick and Churros stands. Well, so much for the veracity of the Authenticity Police!
Here is a German cookbook from the year 1533, translated into English. Use goodies from here!