I’m not sure. At least I haven’t found anything authoritative on the subject. The word itself means the same thing in English as in French, which is to say a money manager, or a person who owns, handles or invests large amounts of capital. As I mentioned in an earlier post, some people believe it’s the “gold bar” shape of the cake that inspired the name. Others because it was (supposedly) invented at a pastry shop located near the Paris stock exchange, the Paris Bourse.
Reader Rainey introduced me to one I hadn’t heard but which has a great intuitive appeal, that they’re called “financiers” because they’re extremely rich. Curious as to whether French speakers use that same idiom to describe both a person of wealth AND a food high in fat, I set Mrs. Pastry to the task over at the U of L modern languages department. Indeed it does check out, at least as far as she can tell. So whether or not it’s actually accurate, it’s certainly my favorite explanation for the name. Thanks Rainey!