Banana rum cupcakes with chocolate frosting

While these little puppies seemed to be a hit, I think they have a way to go before I'm happy with the recipe.
I found a box of banana cake mix in my hunt for spice cake mix, and couldn't pass it up. I thought the Eel liked banana, but couldn't quite remember and just decided to go for it, just in case. Luckily my memory was correct.
I followed the recipe on the box almost exactly, although I did substitute a tbsp or so of water for a tbsp of spiced rum. :o)
The batter came out WAY too loose and watery for my liking, and I was concerned about cooking time. I knew if I had to cook them for a million years until they set, that they ran the risk of getting all chewy and weird. They did. Maybe it was just disappointing to my sophisticated palate, but they definitely need work.
Maybe next time I'll just go with my banana bread recipe and tweak it from there? I feel like I definitely need to work on the frosting; the can of chocolate I used (low Sugar Splenda stuff, shhhh, don't tell) overpowered the banana flavor a bit. Perhaps a ganache next time, or maybe I'll just go for muffins with chocolate chips sprinkled on top before they bake, or smooshed in while they're still warm. Oh yum, now I'm hungry.