Preheat oven to 350°F. Prepare two 8x4-inch bread pans by lining them with a parchment paper sling or greasing and flouring the bottom and sides of the pans.
Melt the chopped unsweetened chocolate by placing it in a small microwave-safe bowl and melting it in short 20 second bursts in the microwave, stirring between each burst of heat. It should only take about 1 minute to 1 minute 20 seconds to completely melt the chocolate. Set aside.
4 ounces unsweetened chocolate
Wash and grate the zucchini, leaving the skin on. Because zucchini can vary greatly in size, you may need two small zucchini or one large zucchini or only part of a gigantic zucchini. If you have way too much zucchini to deal with, you can always grate it and freeze in 2 cup amounts in freezer-safe ziploc bags for future use. Set grated zucchini aside.
3 cups zucchini
Whisk together the flour, salt, baking soda, baking powder, and cinnamon in a medium bowl and set aside.
2 cups all-purpose flour, 1 teaspoon salt, 1 teaspoon baking soda, ½ teaspoon baking powder, ½ teaspoon ground cinnamon
In a large mixing bowl, beat the eggs for 1 minute, then add the granulated sugar, reserving 2 teaspoons for topping the bread, along with the brown sugar, oil, melted chocolate, and vanilla and beat well until totally combined. Stir in the zucchini.
4 large eggs, ¾ cup granulated sugar, ¾ cup brown sugar, ¾ cup vegetable oil, 1 teaspoon pure vanilla extract
Mix in the dry ingredients just until combined, then stir in the chocolate chips and pour the batter evenly into the two prepared bread pans. Sprinkle 1 teaspoon of granulated sugar over the top of each loaf before baking. Alternatively, you could sprinkle a handful of chocolate chips over the loaves before baking, but I like the bit of crunch the sugar gives.
1 cup semisweet chocolate chips
Bake for 45-55 minutes, until a cake tester or toothpick inserted into the center of each loaf comes out clean. Cool completely in the pan before removing and slicing.