01 - Preheat the oven to 350°F. Grease and flour a 9x5-inch loaf pan or line it with parchment paper.
02 - In a large bowl, whisk together mashed bananas, eggs, oil (or butter), yogurt (or sour cream), sugar, and vanilla extract until well combined.
03 - In another bowl, sift together flour, baking soda, salt, and cinnamon.
04 - Gently fold the dry ingredients into the wet mixture, mixing just until incorporated. Do not overmix.
05 - Stir in nuts and/or chocolate chips if using.
06 - Pour the batter into the prepared loaf pan and smooth the top.
07 - Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs (not wet batter).
08 - Remove from oven and let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.