Preheat your waffle maker according to the manufacturer’s instructions.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
In a separate bowl, whisk together the mashed banana, oat milk, vegetable oil, and maple syrup.
Add the wet ingredients to the dry ingredients and whisk until just combined. Do not overmix, or the waffles will be tough.
Stir in the blueberries (if using).
Pour the batter into the waffle maker and cook according to the manufacturer’s instructions.
Serve immediately with your favorite toppings.