Preheat your oven to 350°F (180°C). Line a 9x5-inch loaf pan with parchment paper or lightly grease it.
If using whole rolled oats, blend them in a blender or food processor until finely ground into oat flour.
In a large bowl, mash the ripe bananas until smooth.
Add the eggs, maple syrup, milk, and vanilla extract to the mashed bananas. Whisk until fully combined.
In a separate bowl, mix together the oat flour, baking soda, baking powder, cinnamon, and salt.
Add the dry ingredients to the wet mixture and stir gently until just combined. Do not overmix.
Fold in any optional add-ins such as chopped walnuts or chocolate chips.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake for 45 to 50 minutes, or until a toothpick inserted in the center comes out mostly clean.
Let the bread cool in the pan for 10 to 15 minutes, then transfer it to a wire rack to cool completely before slicing.