01 - Preheat oven to 350°F. Grease a 9x5-inch loaf pan and line with parchment paper for easy removal.
02 - In a large bowl, whisk together flour, baking soda, salt, and cinnamon until well blended.
03 - In a separate large bowl, whisk melted butter, granulated sugar, and brown sugar until smooth and incorporated.
04 - Beat in eggs one at a time, then mix in vanilla extract, mashed bananas, and sour cream or Greek yogurt until fully combined.
05 - Gently fold dry ingredients into wet ingredients using a spatula until just combined. Avoid overmixing to prevent dense texture.
06 - Fold in chocolate chips and nuts if using, reserving a few chocolate chips for topping.
07 - Transfer batter to prepared loaf pan and sprinkle reserved chocolate chips evenly over the surface.
08 - Bake for 50-60 minutes until a toothpick inserted into the center comes out with just a few moist crumbs.
09 - Cool in pan for 10 minutes, then transfer to wire rack to cool completely before slicing.