Preheat oven to 350° F and grease a 9x5 loaf pan with nonstick baking spray. For easy removal from the pan, line with parchment paper as well.
In a large mixing bowl, add the melted butter and sugar and whisk until combined.
8 tablespoons butter, ¾ cup white sugar
Then add the egg, milk and vanilla and mix well.
¼ cup milk, 1 large egg, 1 teaspoon vanilla extract
In a separate bowl, add the flour, cocoa powder, baking powder, baking soda, and cinnamon and stir to combine.
1 ¼ cups all purpose flour, ¼ cup unsweetened cocoa powder, ½ teaspoon baking powder, ½ teaspoon baking soda, ¼ teaspoon ground cinnamon
Add the dry ingredients to the wet ingredients and stir until they are just barely incorporated. Be careful not to over-mix or the bread will be too dense.
Next, add the shredded zucchini and chocolate chips and gently stir into the batter.
1 cup shredded zucchini, ½ cup chocolate chips
Pour the batter into the greased pan and bake for 50-55 minutes, ,or until a toothpick inserted into the center comes out clean.
Allow the bread to cool in the pan for 10 minutes. Then remove it and allow to cool completely on a wire rack.