Grate zucchini.
Smash ripe bananas with a fork.
In the bowl of food processor, add all dry ingredients except grated zucchini and flour and mix on slow speed until just blended.
Add smashed bananas, beaten eggs and sour cream. Mix again on slow speed until just blended.
Add grated zucchini and take the mixture for another whirl on slow speed.
Add flour about a half cup at a time on slow speed so the flour doesn't fly all over the place. Stop when all is blended.
Spray cooking spray on the bottom of 2 bread pans. Line with parchment paper.
Pour batter equally into bread pans.
Place filled bread pans in the middle of a 350 F degree oven.
Bake for 50 - 60 minutes.
Remove from the oven and allow breads to cool in the pan set on cooling racks.
When the bread has cooled a bit, take a knife and slice around all of the four sides of the bread pan to loosen the bread from the pan.
Turn the bread pan over and tap the bottom of the pan several times, shaking the pan gently while doing so. You will slowly feel the bread release from the pan. If you used parchment paper, this will be very easy and fast.