Preheat oven to 180 degrees C and grease cupcake tray.
With a beater or a food processor whisk the butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition, then add the vanilla.
In a separate bowl mix the flour, salt and baking powder. Gradually combine by hand the flour mix, egg mix, chopped banana and milk.
Divide the mix into the cups of the cupcake tray and bake for 20 minutes, or until a knife inserted in a cupcake comes out clean. Cool completely.
To make the icing, cream the butter with an electric mixer until smooth and glossy, then add vanilla. Turn the mixer to low speed and gradually add the sugar to the butter whilst beating, scraping down the sides of the bowl occasionally.
Add the cream, turn to high speed and beat for 5 minutes until fluffy. Add food colouring, if desired. Decorate the cupcakes.