On the former, it's definitely more chocolate than banana, in my opinion. I know the combo sounds kind of odd, but the banana is almost an afterthought - what with the full cup of cocoa powder and chunks of bittersweet chocolate. It's almost as if the banana is there to give the bread a nice, moist texture, but the banana flavor really only hits you at the end of the taste.
And while it's called Cocoa-Nana BREAD, I'd beg to differ. Texture-wise, this is much closer to pound cake than to, say, banana bread. Part of that is the mixing method; quick breads like banana bread mix the dry and wet ingredients together separately, then stir them together. This bread is made more like a cake, by creaming the butter and sugar, then mixing in the other ingredients.
The result is a dense, thick loaf that really should be called Cocoa-Nana CAKE.
This was delicious served on its own, but it really came to life when I spread it with cherry preserves. Nigella Lawson has a chocolate-cherry trifle recipe that calls for sandwiching chocolate cake like this with cherry preserves, and I really think this would be the perfect base for such a trifle. I didn't have enough leftovers to try it, but I will.
In the meantime, if you want the recipe, head over to Obsessed with Baking.