01 - Preheat your oven to 350°F. Grease and flour a 9x5-inch loaf pan, or line it with parchment paper.
02 - In a large mixing bowl, whisk together the mashed bananas, melted butter, eggs, yogurt or sour cream, and vanilla extract until smooth.
03 - In a separate bowl, stir together the flour, granulated sugar, brown sugar, baking soda, baking powder, salt, and cinnamon.
04 - Gently fold the dry ingredients into the wet mixture, mixing just until combined. Do not overmix.
05 - Fold in nuts or chocolate chips if using.
06 - Pour the batter into the prepared loaf pan and smooth the top with a spatula.
07 - Bake for 50 to 60 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs.
08 - Cool in the pan for 10 minutes, then turn out onto a wire rack to cool completely before slicing.