This recipe is not from a vintage hand-written card in my collection. I got it from Joyce Maynard in the 1990s in exchange for signing up for her newsletter or buying one of her books -- the details escape me. And, as there often is, there's a story with the cake. The exact details also escape me, but I think she originally got the recipe from a friend (Nina), made a few changes (adding sour cream and maple syrup) and then made it numerous times for her mother (Fredelle) and family friends while caring for Fredelle during her last weeks and days.
This is one of those cakes that require the separation of yolks and whites -- kind of a pain as it involves using an extra bowl to beat the whites, but the technique does lighten the cake enough to make it worthwhile. I always add some cream of tartar to the whites to ensure they are not overbeaten (and therefore too dry). Fold the whites in, gently, using a spatula.