Preheat the oven to 350F. Grease an 8x4-inch loaf pan. Set aside.
In a large bowl, whisk mashed banana and oil together until well-combined.
1 cup mashed banana, ⅓ cup neutral oil
Whisk in sugars until incorporated.
½ cup brown sugar, ¼ cup granulated sugar
Add egg and vanilla, and whisk until well-combined.
1 large egg, 1 teaspoon vanilla extract
Stir in flour, baking soda, salt, and cinnamon until combined.
1 ½ cups sifted whole wheat flour, 1 teaspoon baking soda, ½ teaspoon salt, ½ teaspoon ground cinnamon
Add nuts, and whisk until just incorporated.
Pour the batter into your prepared loaf pan, and sprinkle with additional nuts, if using.
½-⅔ cup chopped pecans or walnuts
Bake for about 45-60 minutes, or until a wooden toothpick inserted into the center comes out clean. I check the bread around 25-30 minutes and tent with foil if it is browning too quickly.
Let cool in pan for a 5-10 minutes.
Remove bread to wire cooling rack, and let cool completely before slicing.
Notes
Bananas: Use very ripe bananas (yellow with brown spots) for the best flavor and moisture.
Oil: I use olive oil or light olive oil in this recipe. Any neutral oil will work.
Brown sugar: Light or dark brown sugar will work.
Flour: Be sure to properly measure the flour by either weighing it (click "metric" immediately above the ingredients for the weights) or sifting, lightly spooning into a measuring cup, and leveling. Too much flour will give you dry or doughy bread.
Nuts: You can omit the nuts or replace with chocolate chips, raisins, or dried craisins if you prefer.