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 removal.

Mash the bananas: In a large bowl, mash the bananas until mostly smooth. A few small lumps are fine.

Whisk in the wet ingredients: Add peanut butter, oil, granulated sugar, brown sugar, eggs, and vanilla. Whisk until the mixture looks smooth and glossy.

Combine dry ingredients: In a separate bowl, whisk flour, baking soda, baking powder, salt, and cinnamon. This helps distribute the leaveners evenly.

Bring it together: Add the dry mixture to the wet. Stir gently with a spatula just until you no longer see dry flour. Do not overmix. Fold in chocolate chips or nuts if using.

Fill the pan: Pour the batter into the loaf pan and smooth the top. For a pretty finish, you can add a few chocolate chips or a light sprinkle of sugar on top.

Bake: Bake 55–65 minutes, or until a toothpick inserted in the center comes out mostly clean with a few moist crumbs. If the top is browning too quickly, tent loosely with foil during the last 15 minutes.

Cool properly: Let the loaf cool in the pan for 10–15 minutes, then lift it out and cool on a rack for at least 1 hour before slicing. This sets the crumb and keeps it moist.

Slice and enjoy: Use a serrated knife for clean slices. Serve warm, room temp, or lightly toasted with a smear of peanut butter.