Place bananas in a mixing bowl and mash with a potato masher or the back of a fork. Crack the eggs into the bowl and pour in the milk, vegetable oil, vanilla extract, and brown sugar. Whisk everything together until evenly combined.
Pour the flour, baking powder, cinnamon, and salt into the bowl and fold in with a flat spatula. Mix until just combined — it is okay for there to be some lumps.
Allow the batter to rest while the waffle iron heats up. Once the iron is warm, spray it with oil and add ¼ cup of batter to a mini waffle iron or ½ cup to a standard waffle iron. Cook until the waffle is golden brown.
Repeat the process until all of the batter is used, making sure to spray the waffle iron between each waffle to prevent sticking.
Serve with fresh banana slices, butter, and maple syrup.
Notes
The riper your bananas, the sweeter and more flavorful your waffles will be.
Do not overmix the batter — lumps are okay and will result in lighter, fluffier waffles.
Spray the waffle iron generously between each waffle to prevent sticking.
Leftovers reheat beautifully in the toaster straight from the fridge or freezer.
You can use melted coconut oil or melted butter in place of vegetable oil.
Try stirring in mini chocolate chips, chopped walnuts, or blueberries for fun mix-in variations.