Preheat your oven to 175°C (350°F). Line an 8x8 inch baking dish with parchment paper, leaving overhang for easy removal.
In a large bowl, mash the bananas with a fork until smooth and fragrant, with a few small lumps remaining.
Add honey or maple syrup, melted butter or coconut oil, and vanilla extract to the mashed bananas. Stir until the mixture is well combined and slightly glossy.
In a separate bowl, combine the rolled oats, salt, and cinnamon if using. Lightly toast the oats in a dry pan for a few minutes until fragrant, then add to the wet mixture.
Gently fold the dry ingredients into the wet mixture until just combined. If using chocolate chips or nuts, fold them in now.
Transfer the batter to your prepared baking dish, spreading it out evenly with a spatula. Smooth the top for a uniform appearance.
Bake for 20-25 minutes, or until the top is golden, edges are crisp, and a toothpick inserted into the center comes out with moist crumbs.
Remove from the oven and let cool in the pan for at least 15 minutes. The bars will set as they cool and become easier to slice.
Lift the bars out of the dish using the parchment overhang and transfer to a wire rack. Allow to cool completely before slicing into squares.
Slice into bars and serve at room temperature or warmed. Enjoy the comforting, chewy texture with a hint of vanilla and caramelized banana aroma.
