1. Preheat the oven to 200ºC and grease a standard 12-hole muffin tin.
2. Sift together the flours, baking powder and salt and stir in the sugar and banana.
3. Mix together the melted butter and the egg and dissolve the soda in the milk.
4. Tip both wet mixtures into the dry ingredients and mix quickly with a round-bladed table knife. Don’t over mix, just stir until everything is almost combined.
5. Spoon the mixture into the prepared muffin tins and bake for 12 to 15 minutes until risen and golden. Cool on a wire rack.