Preheat oven to 325 degrees F, and grease and flour a 10-inch loaf pan (or line it with parchment paper). Set aside.
If you haven't already, shred the zucchini and let sit in a strainer while you prep the other ingredients.
In a large mixing bowl, add eggs, melted butter, sour cream or applesauce, milk, sugar and vanilla and mix to combine.
In a separate small bowl combine flour, cocoa, baking soda, baking powder and salt using a pastry cutter, whisk or fork.
Add dry ingredients to wet ingredients and mix to combine. Do not over-mix.
Add in zucchini and mix to combine.
Mix in 1/2 cup chocolate chips.
Spoon batter into prepared baking pan and spread evenly. Top with remaining 1/2 cup chocolate chips. Bake 45-55 minutes or until toothpick comes our clean. Pro tip, check at 45 minutes and if the center is not cooked fully but the top is done, cover loosely with foil and continue baking. Do not over-bake. Let cool in the pan for 20-30 minutes. Remove from pan and cool on wire baking rack.