Place ingredients into a medium bowl (if mixing by hand) or a food processor.
Mix thoroughly until batter has a smooth consistency. (A little bit of lumpiness is fine - that's the nature of bananas - but you'll want it as smooth as possible if you're using a decorating bag or the tip will become clogged.)
I used a Wilton #3 decorating tip here on the treats that are outlined.
*Refrigerate iced treats to avoid spoilage.
Adding the carob powder is optional. This will still make a sweet and tasty icing without it!