Preheat your oven to 350°F and butter a 9×5-inch loaf pan. In the bottom of a large bowl, mash bananas with a potato masher or the back of a wooden spoon until virtually smooth but a few tiny lumps remain. Whisk in egg, then oil, brown sugar, syrup and vanilla extract. Sprinkle baking soda, salt, cinnamon, nutmeg and cloves over mixture and stir until combined. Stir in flour until just combined, then millet.