Preheat the oven to 350°F and line a 9x5-inch loaf pan with parchment paper.
Using the fine side of a box grater, grate the zucchini, reserving its liquid. Next, roughly chop the dark chocolate into bite-sized chunks and set aside.
In a large mixing bowl, whisk together the grated zucchini, eggs, vanilla extract, and coconut sugar, and neutral oil until smooth. Whisk together the flour, cocoa powder, cinnamon, baking powder, baking soda, and salt in a medium mixing bowl. Pour the dry ingredients into the wet and fold together until just combined.
Using a baking spatula, fold 2/3 of the chopped chocolate into the batter, reserving 1/3 for sprinkling over the top of the loaf.
Transfer the batter to the prepared loaf pan, smoothing out the top of the batter. Gently bang the bottom of the pan against the counter to help the batter settle into the pan evenly.
Sprinkle the reserved 1/3 of the chopped chocolate over the top of the loaf. Transfer the pan to the oven and bake for 1 hour and 10 minutes, rotating the pan halfway through baking. The loaf is ready when a toothpick inserted in the centre comes out clean and there are defined cracks on the top of the loaf.
Allow the Chocolate Zucchini Bread to cool in the pan for 10 minutes before transferring the loaf to a cooling rack to cool completely before slicing. Once cool, the loaf can be sliced and enjoyed.