Preheat and Prepare: Preheat your oven to 350°F (175°C). Lightly grease a 9x5-inch loaf pan and line it with parchment paper for easy removal.
Mix the Wet Ingredients: In a large mixing bowl, combine the mashed bananas, unsweetened applesauce, maple syrup, egg, and vanilla extract. Whisk until smooth and well combined.
Add the Dry Ingredients: To the same bowl, add the oat flour, baking soda, salt, and cinnamon. Gently fold the dry ingredients into the wet mixture until just combined. Be careful not to overmix.
Prepare the Topping: In a small bowl, mix the coconut sugar and cinnamon for the topping. Set aside.
Assemble and Bake: Pour the batter into the prepared loaf pan, spreading it evenly with a spatula. Sprinkle the cinnamon-sugar topping generously over the batter, covering the entire surface. Bake in the preheated oven for 45–55 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs. If the top begins to brown too quickly, loosely tent it with aluminum foil.
Cool and Serve: Allow the banana bread to cool in the pan for 10–15 minutes, then transfer it to a wire rack to cool completely. Slice and serve warm or at room temperature.
