Janet UK and others: I think there is a misunderstanding here. The term "sponge" is
often used to refer to just a basic cake....like a chocolate, or spice, or white, or
yellow, etc. I notice many of the pro bakers on TV say "sponge," when they just
mean an unadorned cake layer.

Usually, in the U.S., for most of us anyway, the word "sponge" is followed by the word
"cake," meaning sponge cake which is different from chocolate cake or yellow cake
or whatever.

So "sponge" used by itself can be considered different from "sponge cake."

N.