Preheat your oven to 350°F (177°C) and grease a 9×5-inch loaf pan generously with nonstick spray.
In a large bowl, whisk together the flour, baking powder, baking soda, salt, and ground cinnamon until well combined.
In a separate medium bowl, whisk together the vegetable oil, peanut butter, brown sugar, honey, eggs, milk, and vanilla extract until fully integrated. Pour this wet mixture into your dry ingredients.
Gently stir or whisk until just combined; be careful not to overmix. Fold in shredded zucchini and semi-sweet chocolate chips until evenly incorporated.
Spread the batter evenly into your prepared loaf pan and bake for about 55–70 minutes, loosely covering with aluminum foil halfway through if needed.
Once baked through, let it cool in the pan on a wire rack for an hour before removing it from the pan completely.