1. Preheat your oven to 350°F (175°C) and grease an 8.5×4.5-inch or 9×5-inch loaf pan with butter or non-stick spray.
2. In a large bowl, whisk together the wet ingredients: 1 cup granulated sugar, 1/2 cup optional brown sugar, 3/4 cup oil (canola or olive oil), 2 large eggs, 1 teaspoon vanilla extract, and 1/2 cup optional sour cream.
3. Stir the grated zucchini into the wet ingredients until well combined.
4. In a separate bowl, whisk together the dry ingredients: 1 and 3/4 cups all-purpose flour, 1/2 cup Dutch-process cocoa powder, 1 teaspoon baking soda, 1 teaspoon baking powder, and 1/2 teaspoon salt. Ensure there are no lumps.
5. Slowly fold the dry ingredients into the wet mixture, stirring until just combined. Avoid overmixing to preserve a tender texture.
6. Gently fold in 1 cup of dark chocolate chips, reserving a small handful for topping.
7. Pour the batter into the prepared loaf pan and smooth the top with a spatula.
8. Sprinkle the reserved chocolate chips over the top for an attractive and chocolaty finish.
9. Bake the loaf in the preheated oven for 40-60 minutes. Check doneness by inserting a toothpick into the center; it should come out mostly clean with a few moist crumbs.
10. Once baked, remove the loaf from the oven and let it cool in the pan for about 15 minutes.
11. Carefully transfer the loaf to a wire rack to cool completely before slicing.
12. Serve slices plain or with a dollop of almond butter or alongside a glass of milk for an extra special treat.