For medieval Europe? Well, there is always salted fish. ;)

But since that will definitely win the hearts and minds of your class, here are some other things you might consider.

• The Medieval Cookery website has digitized cookbooks from late antiquity through the early modern-ish era, including some in translation. Note that medieval recipes were not written like modern ones, with lists of ingredients and amounts (like a recipe noted as a meat dish will not say anything about the meat...). But you might find some ideas like how to adapt lasagna to a pre-tomato context.

• Because the Internet loves you and wants you to be happy, the Early English Bread Project has an illustrated guide to breadmaking, Anglo-Saxon style

• Various forms of gingerbread, spice bread, "pepper cakes" were super popular in late medieval Germany. The first dedicated Lebküchner or gingerbread-baker is recorded in Munich civic records in the 14th century! Depending on era and location, the cakes would traditionally be dusted with sugar on top or decorated somehow.

Try here for some recipes too, some friends had a go at a few for a giggle a while back and they appear fairly straightforward. I think the vegetable section would probably be appropriate, if you're restricted to peasant food. Just watch out for the use of spices; like sugar, they would have been expensive. Herbs you should be alright with.

If you were in Iceland I'd tell you to get some wind-dried fish. For a long time it was used as a replacement for bread - which is probably why it is still traditionally eaten with butter smeared on it!