Begin by preheating your oven to 350°F (175°C). Prepare a 9x5-inch loaf pan by greasing it lightly or lining it with parchment paper for easy removal later.
In a medium mixing bowl, combine the finely grated zucchini with the granulated sugar, brown sugar, and vegetable oil. Use a whisk or spatula to mix until the mixture is smooth and well combined.
Add the eggs to the mixture one at a time, mixing well after each addition. Then, add the vanilla extract and stir until the batter is uniform.
In a separate large bowl, whisk together the all-purpose flour, whole wheat flour, baking soda, baking powder, salt, and ground cinnamon until evenly blended.
Slowly pour the dry ingredient mixture into the wet zucchini mixture, stirring gently until just combined. Be careful not to overmix—it's fine if a few streaks of flour remain.
Gently fold in the semi-sweet chocolate chips and chopped nuts (if using) until they are evenly distributed throughout the batter.
Transfer the batter to your prepared loaf pan, using a spatula to smooth out the top for an even bake.
Bake in your preheated oven for 50-60 minutes, or until a toothpick inserted into the center of the bread comes out clean or with just a few moist crumbs.
Once baked, let the bread cool in the pan for about 10 minutes. Carefully transfer it to a wire rack to cool completely before slicing.
Notes
For an elegant touch, dust the top lightly with powdered sugar and serve with cream cheese.