In a medium bowl, whisk together the oats, flour, baking powder, cinnamon, and salt. Set aside.
In another medium bowl, mash the bananas very well, then stir in the maple syrup, oil, rice milk, and vanilla.
Add the banana mixture to the flour mixture and stir until well combined.
Scoop the batter into a non-stick mini donut pan and fill to 3/4 full with batter. If you don't have a mini donut pan, you can make mini muffins instead
Bake for 12 minutes until donuts spring back when gently pressed
Remove the donuts from the oven and allow to cool for 10-15 minutes before removing from the pan
While the donuts are cooling, mix together the glaze: stir together the powdered sugar, maple syrup, and maple extract well until smooth. You can add 1-2 more Tablespoons of powdered sugar to make it thicker. I made the glaze thicker for the photos
Drizzle each donut with glaze immediately before serving