Medieval Spiced Breads and Cakes
Simnel Cakes (Simenel - Old French)
From Elizabeth David (English Bread and Yeast Cookery):
"At one time simnel cakes were made with yeast-leavened dough and baked with a layer of almond paste in the center of the cake. The dough was spiced and enriched with eggs, butter and dried fruit, so that the old simnel cake was another variation of spice cake rather like the one described in the Countess of Kent's recipe on p. 475
"Simnel cakes made on a basis of yeast dough were gradually superseded by ordinary cake batters, and the strip of almond paste or marzipan moved from the centre to the top of the cake, which was originally made for Mothering Sunday. Nowadays it has become associated with Easter."
In a related chapter, the following quote.
"The most interesting of the recipes is perhaps the simple spiced fruit bun, the original of our Good Friday hot cross bun without the cross. These spice buns first became popular in Tudor days, at the same period as the larger spice loaves or cakes, and were no doubt usually made from the same batch of spiced and butter-enriched fruit dough. For a long time bakers were permitted to offer these breads and buns for sale only on special occaisons, as is shown by the following decree issued in 1592, the thirty-sixth year of the reign of Elizabeth I, by the London Clerk of Markets:
"'That no bakers, etc, at any time or times hereafter make, utter, or sell by retail, within or without their houses, unto any of the Queen's subjects any spice cakes, buns, biscuits or other spice bread (being bread out of size and not by law allowed) except it be at burials, or on the Friday before Easter, or at Christmas, upon pain of forfeiture of all such spiced bread to the poor.'" (Stow's Survey of London, 1598 ed., ed. John Strype, 1720, Vol. 2, ch xxiv, p. 441)
So, by the Elizabethean period, simnel was a spice bread. It may or may not have been a spice bread when the Assize of Bread was written. Since the name is derived from the Latin "simila" meaning "fine flour," it is possible that simnel was a fine, white, enriched bread (similar to the German "semmel") that evolved into spice bread then, modernly, into a "biscuit", similar to the evolution which occurred in restons.
The decree proved unenforceable and fell by the wayside sometime in the reign of James I (1603 - 1625)
Panforte
The name essentially means "strong bread," most likely from the use of pepper as one of the spices. The earliest references are from 13th Century monastery accounts where the bread was part of the rents and fees taken in by the monastery. I've found no period recipes for panforte, but I suspect it may have been similar to period gingerbread.
I doubt if panforte was served year-round, but it keeps well and I suspect that in the case of the monastery it was a treat for High Holy Days which were not also fast days.
The specific primary reference is stated to be found in the Miscellanee Storiche Senesi. According to my sources, it is the record of a tithe of "panpepati e mielati" or "pepper and honey bread" on some of the tenants of the Monastery of Montecellesi in Siena paid on February 7, 1205.
Commonly called "panpepato," the bread became known as "panforte" in the 19th Century, apparently as a trade name to tie the bread to the first large scale manufacturer in Siena.
Hot Cross Buns
While the term "hot cross buns" is fairly recent, the idea of the spice bun for Easter is definitely an old one. Such spice breads were a specialty item that bakers were allowed to make only at specific times since they fell outside of the Assize of Bread.
Panettone
Panettone in the recipe William describes probably gets its start in Milan during the 15th Century. It may derive from an earlier large loaf of bread which was served during Christmas as early as the 10th Century. Over the centuries, the loaf became enriched and stuffed with fruit and nuts. Modern panetonne comes in both the mushroom shape and as a large slightly flattened loaf (which probably the original shape). As near as I can tell, it was a commercial product from the start.
As for English recipes, a lot of them use currants, but very few use almonds and those that do use them as almond paste (a take off from simnels, I assume). If you choose to use one, you will probably need to modify the recipe to use your currant and almond mix for a period English bread.