So far I've known that Marie Antionette's saying: let them eat cake is not even something she said, however: the story I've heard is that this was another noblewoman saying: " Qu'ils mangent de la brioche" with brioche being wrongfully translated as cake.

what I've heard is that brioche was a sort of bread made from white flour with eggs and sugar (sort of like wonderbread), in fench laws they had maximum prices for normal bread but not for brioche, in order to curtail abuses a baker had to sell his brioche at the price of normal bread if he didn't have bread left. is any of this something that happened? to me it sounds plausible and a whole lot more possible then "those stupid nobles just didn't know a thing about anything"