Preheat the oven to 350 degrees Fahrenheit.
Line a standard loaf pan (9x5 or 8 1/2 x 4 1/2) with parchment paper and set aside.
If you're doing the cinnamon swirl, whisk together the cinnamon and sugar in a small bowl and set aside.
Add your ripe bananas to a blender and puree. Measure out 1 3/4 cup worth and add to a large mixing bowl.
Add in all remaining wet ingredients and whisk together until smooth.
Add in the dry ingredients, making sure to spoon and level the flour, until smooth.
Add half of the batter to your prepared loaf pan, add in the cinnamon sugar, then top with the remaining batter. Top with crushed walnuts if desired.
Bake for 55-65 minutes or until a toothpick comes out clean. About 62 minutes is usually perfect in my oven, but all ovens are different so keep an eye on it.
Remove from the oven and let cool in the pan for about 15 minutes, then lift out the bread and let cool for at least 1 hour on a wire rack before slicing.
Enjoy as is or top with honey and nut butter or regular butter!