Step 1: Preheat the Oven
Preheat your oven to 350°F (175°C). Grease a 9×5-inch loaf pan with butter or line it with parchment paper for easy removal.

Step 2: Mix Dry Ingredients
In a medium bowl, whisk together the flour, baking soda, salt, and cinnamon (if using). Set aside.

Step 3: Prepare Wet Ingredients
In a large bowl, mash the bananas until smooth. Add the melted butter, granulated sugar, brown sugar, eggs, vanilla extract, and sour cream (or Greek yogurt). Mix until well combined.

Step 4: Combine Wet and Dry Ingredients
Gradually add the dry ingredients to the wet ingredients, stirring gently until just combined. Avoid overmixing to keep the bread tender. Fold in nuts or chocolate chips if desired.

Step 5: Bake the Banana Bread
Pour the batter into the prepared loaf pan and smooth the top with a spatula. Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.

Step 6: Cool and Serve
Let the banana bread cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely before slicing.