Preheat oven to 350°F (175°C). Line an 8 inch by 8 inch baking pan with parchment paper, leaving some overhang for easy removal later.
Add mashed bananas and quick oats to a large mixing bowl. Stir and mix with a spatula until the ingredients are evenly mixed and the oats are fully incorporated. Your batter will be very thick. Stir in the coconut until evenly mixed. You can taste and if the mixture is not sweet enough, you can add 1-3 tbsp of maple syrup to the batter. If adding any mix-ins, add them in now. See notes section for mix-in options.
Transfer the batter into your prepared baking pan. Use a spatula to evenly spread it across the pan and smooth the surface.
Bake for about 20-25 minutes or until the bars are set, lightly golden around the edges and surface and cooked through. Let bars cool fully before removing them from the pan and cutting and serving. Store uneaten bars in an airtight container in the fridge or freezer.
