Mash the bananas in a large bowl until you have little to no chunks left. You can use a hand mixer like I did to speed up the process but a fork works just as good.
Add in the other ingredients and stir until combined well.
Stir in any add in's like chocolate chips or walnuts. Optional!
Pour batter into the greased baking dish and spread out evenly. You can use this time to swirl in melted peanut butter if you'd like :)
Bake for 20-25 min or until toothpick/fork come out clean.
Let cool completely before cutting or they will fall apart. They are VERY fudgy.