1. Preheat oven to 350 degrees Fahrenheit. Line a loaf pan with parchment paper (for easy clean-up) or grease with non-stick spray.
2. Shred the zucchini, then use your hands to scoop up the zucchini shreds and squeeze out any excess liquid. I got about 2 Tablespoons of liquid out of mine. Measure out 1 cup of zucchini, tightly packed, and set it aside.
3. Peel bananas and add to a mixing bowl with the egg, oil, syrup, and vanilla. Use a potato masher or fork to mash the bananas into the egg mixture. Add all remaining ingredients, including zucchini and half of the chocolate, and stir to combine.
4. Pour batter into prepared pan, top with remaining chocolate, and bake for 45-50 minutes, or until golden brown and cooked through.
5. Let bread cool in the pan for a few minutes at room temperature, then transfer to a cooling rack to continue cooling. This bread is best when sliced after completely cooled, though a warm, crumbly slice never hurt anyone. Tightly wrap leftovers in plastic wrap (or store in an airtight container) and keep at room temperature for up to 3 days.