Preparation Steps

• Heat oven to 350°F. Line a 9×5-inch loaf pan with a parchment sling and lightly grease the exposed sides.
• Grate the zucchini on the large holes of a box grater. Measure 1 3/4 cups, then wrap in a clean kitchen towel and wring out well until no liquid drips. Fluff with a fork and set aside.
• In a large bowl, whisk together the flour, cocoa, baking powder, baking soda, fine sea salt, and espresso powder until evenly combined.
• In a separate bowl, vigorously whisk the eggs and granulated sugar for 30–45 seconds until slightly pale. Whisk in the oil, sour cream, and vanilla until smooth and glossy.
• Fold the squeezed zucchini into the wet mixture. Add the dry mixture and stir gently with a spatula just until a few floury streaks remain.
• Fold in 2/3 cup chocolate chips. Scrape the batter into the prepared pan, smooth the top, and tap the pan once on the counter to release air. Sprinkle the remaining 2 tablespoons chips over the surface and add a light pinch of flaky sea salt.
• Let the filled pan rest on the counter for 5 minutes to hydrate the cocoa, then bake for 55–60 minutes, rotating the pan after 40 minutes. If the top darkens too quickly, tent loosely with foil. A tester inserted near the center should come out with a few moist crumbs, not wet batter.
• Cool in the pan for 15 minutes, then lift out using the parchment and cool completely on a rack, at least 1 hour, before slicing with a serrated knife.