Preheat oven to 325 degrees Fahrenheit and grease two regular-sized loaf pans.
In the bowl of an electric mixer, combine zucchini, banana, brown and granulated sugar, eggs, vanilla and butter, scraping the sides of the bowl in between mixing.
In a separate bowl, stir together flour, cinnamon, baking soda, salt, and baking powder. Add to wet mixture and mix until combined. Quickly mix in nuts.
Divine mixture evenly between prepared pans, spread so it's level, then place in the oven and bake for approximately 45 minutes to one hour, or just until a toothpick inserted into the center comes out clean. Mine was done in 50 minutes. Check frequently so you don't over bake it.
Let bread sit in pans and cool for about ten to twenty minutes before carefully removing to a cooling rack to cool completely. Store in air tight container or zip top bags.