In another bowl, whisk together the flour, cocoa powder, baking soda, and salt. Add this to the sugar mixture and stir together until it is about halfway mixed together. The batter will be very thick.
2 cups all-purpose flour, 1/2 cup cocoa powder, 1 teaspoon baking soda, 1 teaspoon salt
Add the zucchini and continue to mix until mostly combined. Reserve about 2 tablespoons of the chocolate chips, and add the remaining to the batter. Continue to stir just until everything is combined. (The batter will still be quite thick - but you should be able to stir everything together.)
1 1/2 cups grated zucchini, 1 cup mini chocolate chips
Transfer the batter to the prepared loaf pan. Spread the batter to an even layer. Top with the reserved chocolate chips.
Bake until a tester inserted in the middle comes out mostly clean, about 1 hour. (When testing, it can be tricky if you hit a chocolate chip, so you may want to test in a few different areas.)
Let the bread cool before removing from the pans to slice and serve.
Notes
Nutrition information provided as an estimate only. Various brands and products can change the counts. Any nutritional information should be used as a general guide.