Prep the pan and oven: Heat the oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line it with a parchment sling for easy lifting.

Mash the bananas: In a large bowl, mash the ripe bananas with a fork until mostly smooth with a few small lumps.

Whisk in wet ingredients: Add peanut butter, oil, eggs, sugar, and vanilla. Whisk until fully combined and glossy. The mixture should look smooth and slightly thick.

Combine dry ingredients: In a separate bowl, whisk flour, baking soda, baking powder, salt, and cinnamon. This prevents clumps and helps even rise.

Fold, don’t beat: Add dry ingredients to the wet mixture. Use a spatula to fold just until no dry streaks remain. Do not overmix or the loaf can turn dense.

Stir in extras: If using chocolate chips or nuts, gently fold them in now.

Pan and top: Scrape the batter into the pan and smooth the top. For a bakery-style look, dollop a little extra peanut butter on top and swirl lightly. You can also sprinkle a few chopped peanuts.

Bake: Bake for 50–60 minutes, until the top is golden and a toothpick inserted in the center comes out with just a few moist crumbs. If the top is browning too fast, tent with foil for the last 10 minutes.

Cool properly: Let the loaf cool in the pan for 10–15 minutes, then lift it out and transfer to a wire rack. Cool at least 45 minutes before slicing to avoid gummy slices.

Serve: Slice and enjoy as is, or warm briefly and spread with a little butter or extra peanut butter.