Preheat your oven to 175°C (350°F). Grease a 9x5 inch loaf pan with butter or non-stick spray, then line it with parchment paper for easy removal.
Use a fork or potato masher to mash the bananas in a large mixing bowl until mostly smooth, leaving some small lumps for texture and aroma.
Stir the peanut butter into the mashed bananas until it’s well incorporated and slightly oozy, creating a rich, fragrant base for the batter.
Add the sugar, eggs, and vanilla extract to the banana-peanut mixture. Whisk everything together until the mixture is smooth, slightly fluffy, and fragrant with nutty notes.
In a separate bowl, whisk together the flour, baking soda, and salt to combine evenly.
Gradually add the dry ingredients to the wet mixture, gently folding with a spatula until just combined. Do not overmix—the batter should be moist, with a few lumps remaining.
Pour the batter into your prepared loaf pan, smoothing the top with a spatula. If desired, sprinkle flaky sea salt on top for a lovely contrast.
Bake in the preheated oven for about 55 to 65 minutes. Check doneness by inserting a toothpick into the center; it should come out moist with crumbs, not wet batter.
If the top browns too quickly, tent the loaf with foil and continue baking until fully cooked. Remove from the oven and let cool in the pan for 15 minutes.
Transfer the bread to a wire rack and let it cool completely before slicing. This allows the crumb to set perfectly and prevents crumbling.
Slice the bread with a serrated knife and enjoy as is, or spread with extra peanut butter or honey for added flavor. Serve warm or at room temperature and savor the cozy, dense crumb filled with swirls of peanut butter.
