1. Preheat oven to 350°F (175°C). Grease a 9×5-inch loaf pan and line with a parchment sling.

2. Grate zucchini and squeeze firmly in a clean towel until damp but not dripping; measure 1 1/2 cups.

3. Whisk flour, cocoa, baking powder, baking soda, salt, and espresso powder (if using) until evenly combined.

4. In a large bowl, whisk granulated sugar, brown sugar, and eggs until smooth; whisk in oil and vanilla.

5. Add dry ingredients to wet and fold gently until a few flour streaks remain; do not overmix.

6. Fold in zucchini and 3/4 cup chocolate chips until just combined and evenly distributed.

7. Transfer batter to the pan, smooth the top, and sprinkle with remaining 1/4 cup chips.

8. Bake 50–60 minutes, until a toothpick inserted in the center comes out with moist crumbs, not wet batter.

9. Cool in pan 10–15 minutes, then lift out to a rack and cool completely before slicing.

10. Slice with a serrated knife; serve slightly warm or at room temperature.