Preheat your waffle iron according to your waffle iron directions.
In a medium sized bowl, mash the bananas well. You want them to be thick and liquidy with few chunks. I like to use a fork to mash the bananas but a potato masher also works well.
2 ripe bananas
Whisk the milk, egg yolks and vanilla into the mashed bananas.
2 egg yolks, 1 cup whole milk, 1 teaspoon vanilla extract
Add the melted butter to the bowl and whisk again.
6 tablespoons melted butter
Stir in the flour, cinnamon, baking powder, brown sugar and salt. Stir until the batter is smooth.
1 1/4 cup flour, 1 teaspoon ground cinnamon, 2 teaspoons baking powder, 2 tablespoons brown sugar, 1/4 teaspoon salt
Pour about ¾ of a cup of waffle batter into your waffle iron. Each waffle iron will be different so check your waffle iron instructions to see how much batter to add. ¾ cup batter is perfect for a regular sized Belgian waffle.
Close the waffle iron and cook for about 4-5 minutes. The waffle will be golden brown and pull away easily from the waffle iron. Remove the cooked waffle from the waffle iron using tongs.
Serve the waffle while hot and repeat the cooking process with the remaining batter.