Preheat oven to 180°C and grease a 12-hole muffin pan.
Process butter, caster sugar, banana, eggs and vanilla in a food processor until well combined.
Place flour, baking powder, coconut and chocolate in a large bowl, then fold in banana mixture. Place spoonfuls into the muffin pan.
Bake for 15 - 20 minutes or until risen and golden. Cool slightly in the pan, then turn out onto a rack to cool completely. Serve dusted with icing sugar (optional).