Placenta cake is not what you might at first think. To the ancient Romans, placenta, like its erstwhile fellow, libum, were cakes made with honey to be used in important religious services. It should, of course, be remembered that honey took the place of our sugar and given humankind's love of all things sweet, these cakes were probably popular everyday treats.
The Latin placenta is named after the Greek plakous which is often translated as "cheese cake" because the chief ingredients were flour, cheese and honey. The recipe survives to us in section 76 of Marcus Cato the Elder's De Agricultura (On Agriculture), which we have reproduced (left) from the Bill Theyer's translation on his excellent website, Lacus Curtius. It is worth noting that Cato's recipe makes a half modius cake. Be warned, a modius is an ancient Roman unit for dry measures equivalent to 8.72 l (8.72 kg; roughly a peck) so this is a seriously big cake!
At a later date we will update this post with a placenta recipe using more practical quantities of ingredients. We will also add one for libum, just in case you need to win favour with the gods in these trying times.
1. Dalby, A. (2003), Food in the Ancient World from A to Z, Routledge Press, London, p. 70.
2. Thayer, W, De Agricultura by Cato the Elder, Lacus Curtius, retrieved May 8th, 2020.