Silver the flour, cocoa powder,baking powder , baking soda, salt together. Keep aside. Mix sugar to this as well
Whisk the egg, mashed banana, water, milk, oil and vanilla extract together. Fold in the dry ingredients to the wet mixture.
Line the muffin tray with cupcake liners. Fill every cup to 3/4 th amount. Bake at 180℃ in a preheated oven for 20 minutes.
Whisk butter until fluffy. Add the icing sugar and whisk further.
Add the vanilla extract and cream, whisk further until piping consistency is achieved.
Add the yellow colour and give it a mix. Pour this into a piping bag, pipe the cupcakes.