I use dried raisins or currants rather than fresh grapes. The word for grape in French is raisin, which confuses the issue somewhat as it can mean either fresh or dried grapes (known in English as raisins) depending on the context. The first translation of this recipe that I used called for raisins and I found the results very appropriate. I'd like to hear results from anyone who has tried this with fresh grapes.
Although 'cakes' in period would have been sweetened yeast cakes or shortbreads, I go ahead and use some pound cake or angelfood cake in my breadcrumbs for the additional sweetness. Leave these out if you choose, or if you object to the leavening in them.
I have tried leaving the almonds in rather than straining them out, but do not like the grainy texture that this gives to the finished product.
This makes a nice, make-ahead dish for a feast. The slices are moist, but hold their shape. The flavor is mild and pleasant - rather reminiscent of a slice of Christmas pudding but less rich and less spicy.
Take fine raisins, boiled milk of almonds, scalded, cakes and crusts of white bread and apples cut into small cubes and boil your milk and add saffron to colour it and sugar and put all in together until it is thick enough to be cut. It is served in Lent, instead of rice.
Ménagier de Paris, ~1395; Mistress Elaina de Sinistre (SCA)