Preheat oven to 350°F. Grease a loaf pan or line with parchment paper and set aside.
Combine bananas, orange juice and zest, rolled oats, and maple syrup in a large bowl. Let the oats sit for 20 minutes to soften and soak up some of the liquid.
Combine ground flax and water and set aside to thicken.
In a separate bowl, whisk together oat flour, chickpea flour, cinnamon, baking powder, and baking soda.
When the oats have softened, add in almond butter, vanilla extract, and flax mixture and mix until well combined.
Add wet ingredients to dry and mix until just combined. Fold in chocolate chips and walnuts.
Pour batter into loaf pan and bake for 60-75 minutes, until a toothpick inserted in the center comes out clean. Poke a few times since you may poke a chocolate chip which will come out messy. Let the bread cool in the pan for 5-10 minutes, then transfer to a cooling rack to cool completely.
Notes
*Ensure your oats/oat flour are gluten-free if this is an issue for you.