Preheat oven to 350 degrees F. Grease a 9x5 inch loaf pan. I suggest lining it lengthwise with a strip of parchment paper for easy lifting, but that is optional.
Sift together the flour, baking soda, salt and cinnamon, then whisk to make sure dry ingredients are well blended.
Beat sugar and eggs with a whisk until light and fluffy, about 10 minutes (I used a stand mixer with whisk attachment for this). Drizzle in the oil. Add mashed bananas, creme fraiche or sour cream, and vanilla.
Fold in the flour mixture and stir until blended, then stir in the nuts (if using).
Pour batter into the prepared pan and bake at 350 for 45 minutes to an hour. My loaves usually take a full hour.
Notes
I used about 1 ½ cups or 12 oz weight total bananas.