Preheat oven to 350℉.
In a medium mixing bowl, whisk together flour, cinnamon, baking soda, baking powder, and salt.
In a large mixing bowl, mash bananas.
Beat sugar into bananas until combined.
Mix in oil, eggs, and vanilla.
Stir dry ingredients into banana mixture.
If using walnuts, stir them into batter.
Pour baatter into parchment lined loaf pan.
Bake 1hr, 10min or until a test stick comes out clean.