Preheat your oven to 350°F (175°C) and grease a 9x5-inch loaf pan.
In a medium bowl, combine the grated zucchini, brown sugar, granulated sugar, vegetable oil, eggs, and vanilla extract. Mix until well blended.
In a separate large bowl, whisk together the all-purpose flour, whole wheat flour, baking soda, baking powder, salt, and ground cinnamon.
Gradually add the wet ingredients to the dry ingredients, stirring gently until just combined. Be careful not to over-mix.
Fold in the chocolate chips and walnuts (if using) until evenly distributed throughout the batter.
Pour the batter into the prepared loaf pan, smoothing the top with a spatula.
Bake for 55-60 minutes or until a toothpick inserted into the center comes out clean.
Remove from the oven and let the bread cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.
Notes
Slice the bread and serve warm with a sprinkle of powdered sugar on top or a dollop of cream cheese spread on the side. Decorate with a few chocolate chips and a sprig of mint for color.