It's more of a dense block than a fluffy cake, but it's good, and it's even good for you, even with the chocolate.
4 small or 3 large overripe bananas
1/2 cup softened butter, margarine or oil (Or try applesauce, that's my next variation, to make it low fat)
3/4 cup sugar
1 TBS vanilla
4 small or 3 large eggs
blend it all up.
1 3/4 cups whole wheat flour
1 tsp baking powder
a small pinch of salt
1 tsp of cinnamon
blend it all up
Add the dry to the wet and put it into a greased (or sprayed with that non-stick stuff) 9 by 6 cake pan or some equivalent. Muffin tins would work
sprinkle on some cinnamon
Now for the chocolate bit.
I have this stuff I bought from Twinings called chocolate indulgence, which is basically finely-ground dark chocolate.
I sprinkle that all over the top of the cake. It melts into a yummy crust.
Failing that, you can use chocolate chips, or a mixture of cocoa powder and sugar, I'd think.
Now if you used the powdery stuff, take a knife or spatula and swirl through the top of the cake, making streaks of chocolate in among the banana batter.
Bake at 325 for about 40 minutes for the cake pan, 20-25 for the muffins.