Preheat oven to 180°C (350°F). Place the flour, baking powder, sugar, eggs, oil, buttermilk and vanilla in a bowl and mix until just combined. Gently fold through the banana and chocolate chips. Divide the mixture between 12 x ½ cup-capacity (125ml) muffin tins lined with paper patty cases and bake for 25–30 minutes or until golden or cooked when tested with a skewer. Turn out onto a wire rack to cool. Dust with icing sugar to serve. Makes 12.