1. Preheat the oven to 180 degrees and grease loaf pan.
2. Place the butter and sugar in the bowl of an electric mixer and beat until light and creamy.
3. Add the egg and beat well. Add the flour, baking powder, coconut, milk, mashed banana and cinnamon and fold until well mixed.
4. Spoon mixture into pan and place banana slices on top. Brush with the melted butter and sprinkle with caster sugar.
5. Bake for 35 minutes or until golden brown and cooked all the way through.
6. Serve warm or cold.