preheat oven to 180 (i put them on 160 fan forced) Whisk flour, cocoa powder, baking soda and salt in a large bowl. Combine sugar, oil, egg, buttermilk and vanilla in a medium bowl. Add wet ingredients to dry, and stir until just moist. Fold in mashed bananas, followed by chocolate chips if using. Empty batter into a 9 x 5 loaf pan lined with baking paper. sprinkle sugar/nuts on top if wished ( I only put nuts on half- for nut free school lunches) Bake for 55 minutes to an hour. cool on a rack cut into slices wrapped up for snacks on the go Serves 12