Sift the flour and baking powder into a bowl and stir in the caster sugar. Mix together the mashed banana, egg, honey and melted butter in a separate bowl, then add to the dry ingredients. Stir in the raspberries until mixed.
Spoon the mixture into the cake cases and bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 15 minutes until golden and just firm to the touch. Leave to cool slightly.
Mix the icing sugar with the measurement water to make a smooth icing. Add a drop of pink food colouring and stir to mix. Spoon on to the buns and decorate with sugar flowers.