Unlike the basic (and often boring) zucchini bread, this quick bread is saturated with citrusy orange flavor thanks to a simple step of rubbing orange zest into the sugar. This draws out the zest’s essential oils and evenly distributes them for bright flavor throughout the loaf, which also is studded with chunks of bittersweet chocolate. Ample zucchini shreds dot the crumb with flecks of green and keep it amazingly moist, but the summer squash flavor disappears into the background. We also sprinkle the bread, inspired by a recipe from “Tartine” by Elisabeth M. Prueitt and Chad Robertson, with turbinado sugar, a coarse, golden raw sugar, to add a crystalline crunch and sparkle. If you can’t find turbinado, use an equal amount of white sugar. Tightly wrapped and refrigerated, the loaf will keep for up to five days; bring to room temperature to serve.