Heat oven to 350°F and arrange a rack on the bottom. Grease a 9x5in loaf pan.
Mash bananas in a large bowl with a potato masher until very few pieces remain. Whisk in the egg, then add the coconut oil, brown sugar, maple syrup, and vanilla, whisk until smooth.
Sprinkle the baking soda, salt, cinnamon, nutmeg, and cloves over the banana mixture and whisk to combine. Whisk in the flour until completely incorporated. Switch to a rubber spatula and fold in the millet and chocolate chips.
Scrape batter into prepared pan and bake in the bottom of the oven for 50-60 minutes or until a toothpick inserted in the middle comes out clean. If the bread is getting too dark, cover loosely with foil until bread is baked all the way through. Cool in pan on a rack for 15 minutes, then turn out of the pan and cool completely.