Preheat oven to 350F (175C). Grease and flour a 9x5 inch loaf pan.
In a large bowl, mash the bananas until smooth.
Stir in the oil, sugar, egg, and vanilla extract until well combined.
In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon (if using).
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
Pour the batter into the prepared loaf pan.
Bake for 50-60 minutes, or until a wooden skewer inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.
Optional Tips:
- For a richer flavor, substitute brown sugar for granulated sugar.
- Chopped nuts (walnuts or pecans) or chocolate chips can be added to the batter for extra texture and flavor.
- If the top of the bread is browning too quickly, tent it with foil during the last 15-20 minutes of baking.
- For a vegan version, substitute the egg with a flax egg (1 tablespoon flaxseed meal mixed with 3 tablespoons water, let sit for 5 minutes).