In a medium bowl, combine mashed bananas, eggs, butter and sugar and extract.
Mix thoroughly, then add dry ingredients; flour, baking powder, salt and cinnamon.
Mix until combined then stir in chopped walnuts.
Pour batter into baking dish.
Make streusel topping.
Combine flour, butter and sugar until crumbly.
Sprinkle on top of batter.
Bake for 1 hour to 1 hour and 10 minutes.
Allow to cool before slicing.
Video
Notes
You don’t need the banana extract to make this taste better. I just enjoy a strong banana flavor. You can substitute with vanilla extract if you’d like.