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 combined.
03 - In another bowl, whisk melted butter, granulated sugar, and brown sugar until smooth. Beat in eggs one at a time.
04 - Mix in vanilla extract, mashed bananas, and sour cream until fully incorporated and smooth.
05 - Gently fold dry ingredients into wet mixture with spatula until just combined. Do not overmix.
06 - Fold in chocolate chips and nuts if using, reserving a few chips for topping.
07 - Pour batter into prepared pan. Sprinkle reserved chips on top. Bake 50-60 minutes until toothpick inserted comes out with few moist crumbs.
08 - Cool in pan 10 minutes, then transfer to wire rack to cool completely before slicing.