I have flourless brownie recipes using black beans or sweet potato, which you can really tell have something other than flour in them, but exactly-what is not as obvious as with banana. The black bean one has kind of a coffee flavor (just from the black beans, no coffee added) and fudgey texture. The sweet-potato one kind of tastes... vegetable-y? I think it needs more tweaking to really suit my taste.

Flourless brownie recipe swap meet!