Pre-heat the oven to 350°F and line an 8" x 8" baking pan with parchment. Mash ripe bananas in a large bowl until creamy. Mix in creamy peanut butter, pure maple syrup, and vanilla.
Stir the oats, sea salt, and cinnamon (dry ingredients) into the large bowl with the wet ingredients until a thick dough forms. If adding, mix chocolate chips into the dough.
Use a rubber spatula to evenly distribute the banana peanut butter oat mixture in the baking pan. Sprinkle chocolate chips on the batter if desired.
Place the baking dish on the centre rack of the preheated oven and bake for 20–25 minutes until the healthy banana muesli bars are golden brown and firm when poked.
Slice and serve the bars after they cool to room temperature.