Preheat oven to 375°F
Use a fork to mash the banana in a small bowl.
Place flour, oats, peanut butter, mashed banana, coconut oil, and eggs in a large bowl.
Mix well until a dough is formed.
Spoon the mixture into an ungreased non-stick donut pan.
Press the mixture down into the pan. The donuts will not rise so you don’t want to leave any gaps in the dough.
Bake at 375°F for 14 to 16 minutes.
Remove the donuts from the pan place them on a wire rack to cool to room temperature.
If desired, spread peanut butter on top of the donuts for the icing and decorate with any desired toppings.