Preheat and prep: Heat your oven to 350°F (175°C).
Line a 9x5-inch loaf pan with parchment paper or grease it lightly.
Mash the bananas: In a large bowl, mash the ripe bananas until mostly smooth with a few small lumps.
Whisk in wet ingredients: Add brown sugar, oil, plant milk, vanilla, and vinegar. Whisk until well combined and glossy.
Combine dry ingredients: In a separate bowl, whisk flour, baking powder, baking soda, salt, and cinnamon.
Fold together: Add the dry mixture to the wet mixture. Use a spatula to fold until just combined. Do not overmix; a few streaks of flour are okay.
Add mix-ins: Gently fold in nuts or chocolate chips if using.
Save a few for sprinkling on top.
Fill the pan: Pour the batter into the prepared loaf pan and smooth the top. Sprinkle remaining mix-ins, if desired.
Bake: Bake for 50–60 minutes. The loaf is done when a toothpick inserted in the center comes out mostly clean with a few moist crumbs.
Cool: Let the bread cool in the pan for 10–15 minutes.
Then lift it out using the parchment and cool completely on a rack before slicing.
Slice and serve: Use a serrated knife for neat slices. Enjoy warm or at room temperature.