For the past few years I've been making a traditional plum pudding at Christmastime. The recipe I use is a sort of average of the one from the Better Homes cookbook, and several that I found online. This year, as I was mixing it up and putting it into the pudding mold, I was musing over how medieval the recipe seemed.
First, it's a holiday recipe that contains lots of dried fruits and spices. This is typical of a lot of medieval dishes, where imported fruits and spices served both to excite the palate and to blatantly advertise how wealthy the host was. Also, the general form of the dish - a boiled pudding - is in itself very typical of the middle ages. A prime example is Wastels Yfarced, a recipe where a bread crust is hollowed out, the crumb is mixed with eggs, currants, and spices, is put back into the crust, and then the whole thing is boiled. Add to this dishes like haggis, and some "sausages" where often little or no meat is used, and the filling is stuffed into an animal stomach or intestines and boiled.
So plum pudding is probably medieval too, right? Sadly, no. Oddly, I've found very few medieval recipes for boiled puddings that are desserts - almost all of them are savory dishes. The really big clue though is the inclusion of baking powder or baking soda. This makes the pudding turn out something more like modern cake, and neither baking powder or baking soda were used in cooking until after the sixteenth century. My guess is that somewhere in England in the late seventeenth century, a cook decided to experiment and crossed a medieval-style pudding with a new cake recipe. That, or they put the baking soda in by accident (it happens). Either way, whoever that cook was, I am forever in their debt.