Heat oven to 350 degrees.
Make this in the Ninja for easy cleanup. Place ingredients in the Ninja in the order listed.
Beat 2 eggs by pulsing.
Add melted butter and mix on 1 for a few seconds.
Break up 3 to 4 bananas, drop them in and mix.
Add vanilla, baking soda, and salt. Mix.
Add brown sugar and mix.
Add flour one cup at a time and mix.
Remove the blade and then add the walnuts and fold them into the batter.
In a greased and floured pan, pour in the batter. Bake for about an hour or until a toothpick or skewer comes out clean. Do not overbake.
