Preheat the oven to 350 degrees . In a bowl, whisk together the egg, honey, bananas and peanut butter. Stir in 3 cups water; whisk until smooth.
In a separate bowl, stir together the flour, baking powder and cinnamon; add to the egg mixture.
Spray two 12-cup muffin pans with cooking spray; fill each cup three quarters full. Bake until browned, about 30 minutes. Let cool.