Step 1: Preheat your oven to 350°F (175°C). Lightly grease and flour a 9x5-inch loaf pan, or line with parchment paper.
Step 2: In a large bowl, mash the very ripe bananas with a fork until mostly smooth but with a few small lumps remaining.
Step 3: In a separate medium bowl, whisk together the melted butter, granulated sugar, and brown sugar until well combined. Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.
Step 4: Pour the wet ingredients into the bowl with the mashed bananas. Mix gently until just combined.
Step 5: In another medium bowl, whisk together the all-purpose flour, baking soda, ground cinnamon, and salt.
Step 6: Gradually add the dry ingredients to the wet ingredients, mixing with a spatula or wooden spoon until just combined. Do not overmix; a few streaks of flour are acceptable.
Step 7: If adding optional mix-ins like chocolate chips or nuts, gently fold them into the batter now.
Step 8: Pour the batter into your prepared loaf pan and spread it evenly.
Step 9: Bake for 55-65 minutes, or until a wooden skewer inserted into the center comes out clean. If the top browns too quickly, tent loosely with foil.
Step 10: Remove the pan from the oven and let it cool in the pan on a wire rack for 10-15 minutes.
Step 11: Carefully lift the banana bread out of the pan (using parchment paper if applicable) and let it cool completely on the wire rack before slicing. For optimal freshness, once completely cooled, store any leftovers in sturdy Basics Glass Food Storage containers.