Step 1: Preheat your oven to 350°F (175°C). Grease and flour a 9×5 inch loaf pan, or line it with parchment paper, leaving an overhang on the longer sides.
Step 2: In a large bowl, mash the ripe bananas thoroughly with a fork until mostly smooth, leaving a few small lumps for texture if you like.
Step 3: Add the melted butter to the mashed bananas and stir until well combined. Then, stir in the granulated sugar (and brown sugar, if using), the beaten egg, and the vanilla extract. Mix until everything is just combined.
Step 4: In a separate medium bowl, whisk together the all-purpose flour, baking soda, and a pinch of salt.
Step 5: Gradually add the dry ingredients to the wet ingredients. Using a spatula, fold them together gently until just combined. Do not overmix.
Step 6: If you’re using optional mix-ins like chopped walnuts or chocolate chips, gently fold them into the batter now.
Step 7: Pour the banana bread batter into the prepared loaf pan and spread it evenly. Optionally, sprinkle a little extra granulated or demerara sugar on top.
Step 8: Bake for 55-65 minutes, or until a wooden skewer or toothpick inserted into the center comes out clean. If the top browns too quickly, loosely tent with aluminum foil.
Step 9: Once baked, remove the banana bread from the oven and let it cool in the pan on a wire rack for about 10-15 minutes.
Step 10: After cooling slightly in the pan, use the parchment paper overhang or carefully invert the banana bread onto the wire rack to cool completely. Slice and enjoy!