Mash a banana in a mixing bowl with a fork, then add the rest of the ingredients for the batter. Gently fold the ingredients together with a spatula until no more powder is visible.
Evenly divide the batter among 6 Texas-size cupcake molds (or 8-10 standard-size cupcake molds).
Bake in the oven for about 12 – 15 minutes at 350F, or until you can stick a toothpick in one and it comes out clean. Set aside to cool in the molds.
In another bowl, whisk together the ingredients for the icing. Then place in a sealable bag, like a Ziploc bag, and cut the corner off to create an icing piping bag.
Once the cupcakes have cooled, put a little icing on each one and garnish with a banana slice. Enjoy!