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 another 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, mashed bananas, and sour cream or yogurt until fully combined.
05 - Gently fold dry ingredients into wet mixture with a spatula until just combined. Avoid overmixing to prevent tough texture.
06 - Fold in chocolate chips and nuts if using, reserving a few chips for topping.
07 - Transfer batter to prepared loaf pan and sprinkle reserved chocolate chips on surface.
08 - Bake for 50 to 60 minutes until a toothpick inserted into the center emerges with a few moist crumbs.
09 - Let cool in pan for 10 minutes, then remove to wire rack to cool completely before slicing.