Preheat the oven to 350 degrees and grease a medium (8 1/2 by 4 1/2 inch) loaf pan.
Blend the oats in a high powered blender for about 30 seconds, or until they form a fine flour. (Alternately, you can use 2 1/4 cups oat flour). Add the baking powder, baking soda, and salt and process briefly. Transfer the dry ingredients to a bowl.
Using the same blender, add the bananas, eggs, coconut milk, melted coconut oil, and pure maple syrup. Blend for about 10 seconds to combine the liquid ingredients. (Alternately, you can mash the bananas by hand, then stir together the wet ingredients in a large bowl.)
Transfer the wet ingredients to a large bowl, and stir in the dry ingredients. The batter will be quite thin.
Transfer the batter to the prepared loaf pan. Bake for 50 minutes, or until the bread is nicely browned and a toothpick inserted in the center of the loaf comes out clean.
Cool on a wire rack for 10 minutes in the pan, then remove the bread from the pan. Cool completely on the rack.
Store in an airtight container for up to 3 days, or freeze for later.