Preheat your oven to 350°F; grease and flour a 9" x 5" loaf pan and set aside.
In a medium sized mixing bowl, combine the dry ingredients and mix with a flat whisk until well combined.
In a separate bowl, combine the bananas, melted coconut oil, maple syrup, buttermilk, eggs and vanilla extract. Mix the ingredients with a whisk until well combined and practically lump free, mashing the bananas as you go.
Add the grated zucchini and mix with a spatula until well incorporated, then add the dry ingredients all at once and stir until just incorporated.
Transfer the batter to your prepared pan, spread evenly and sprinkle with maple sugar flakes if desired.
Bake for 50 to 55 minutes or until the top is a beautiful golden brown and a toothpick inserted in the center comes out clean.
Allow the loaf to cool in the pan for about 5 minutes, then unmold it and place it on a cooling rack to cool completely.