Preheat oven to 350 degrees.
In a large bowl add bananas and mash with a fork. Add grated zucchini, eggs, vanilla, and melted butter.
In a separate bowl combine dry ingredients: flour, sugar, baking powder, baking soda, cinnamon, and salt. Stir to combine.
Gently fold the dry ingredients into the wet ones in stages until combine. Be careful not to over mix. Add chocolate chips and mix until incorporated.
Transfer batter to lined cupcake tray, filling each cup about ¾ of the way full.
Bake muffins for 25-30 minutes, or until tops are brown and a toothpick comes out clean.