Preheat oven to 350ºF. Spray a standard loaf pan (8.5" x 4.5") with cooking spray and set aside.
In a medium bowl, add flour, cinnamon, baking soda, baking powder, and salt. Whisk to combine and set aside.
In a large bowl, beat eggs with a whisk until yolks and whites are well blended and eggs are just lightly fluffy.
Add both sugars to eggs and whisk to combine. Add oil and vanilla and whisk to combine.
Add about a third of the flour mixture to the egg mixture and stir just until combined using a wooden spoon or rubber spatula. Add about a third of the grated zucchini to the mixture and stir to combine. Repeat two more times until all of the flour mixture and grated zucchini has been added and stirred into the batter just until combined. Do not over mix the batter.
Add 1 cup (170 grams) chocolate chips (if using) to the batter and stir just until they're evenly distributed throughout the batter.
Pour the batter into the prepared loaf pan and sprinkle the remaining ¼ cup (43 grams) chocolate chips over the batter.
Bake the zucchini bread for 1 hour or until golden brown and a toothpick inserted into the center of the loaf comes out clean.
Let the loaf cool in the pan on a wire rack before removing it from the pan and letting it cool completely on a wire rack.
Notes
Storage: Store zucchini bread in a sealed (but not airtight) container at room temperature for up to 5 days. I love to store it in a bread box.Freezing: Zucchini bread can also be frozen for up to 3 months; for best results, wrap the completely cooled loaf tightly in plastic wrap followed by a layer of aluminum foil and a plastic bag or other airtight container before freezing.Zucchini Bread Muffins: To make zucchini bread muffins, prepare the batter as directed. Line a standard muffin pan with paper liners and divide the batter evenly among the muffin liners (about 3 Tablespoons of batter per muffin). Top the muffins with the reserved ¼ cup chocolate chips (if using) and bake at 350ºF for 20-25 minutes, until muffins are puffed and golden and a cake tester inserted into the center of the muffin comes out clean. Let muffins cool in the pan on a wire rack before serving. Muffins can be stored in an airtight container at room temperature for up to 4 days or frozen for up to 3 months. Makes 12-16 standard muffins (depending on the size of your muffin pan.)