Preheat your oven to 350°F (175°C) and lightly grease a donut pan with cooking spray.
In a mixing bowl, combine the mashed bananas, oat flour, peanut butter, honey or maple syrup, eggs, baking powder, cinnamon, and vanilla extract. Stir until well combined. Fold in your optional add-ins such as chopped walnuts and dark chocolate chips.
Spoon the batter into the donut pan, filling each cavity about 3/4 full.
Bake in the preheated oven for 12-15 minutes, or until a toothpick inserted into the donuts comes out clean. Once baked, remove the donuts from the oven and let them cool in the pan for a few minutes. Then transfer them to a wire rack to cool completely.
Once cooled, cover the donuts with melted chocolate and coconut oil (optional) and place to the refrigerator so the topping sets. Enjoy!