Preheat oven to 350°F (175°C). Line the bottoms of two loaf pans with parchment paper and lightly grease the sides.
In a large bowl, combine 1 cup brown sugar, 1 cup white sugar, 1/2 cup unsweetened applesauce, 1/2 cup oil, and 3 large eggs. Beat or whisk until smooth and well combined.
In a separate bowl, whisk together 3 cups all-purpose flour (you may replace up to 1 cup with whole wheat flour), 1 tsp salt, 1 tsp baking soda, 1/4 tsp baking powder, and 1 tbsp cinnamon.
Add the dry mixture to the wet mixture and stir gently until just combined—do not overmix.
Fold in 2 cups grated zucchini and 1 tbsp vanilla extract until evenly distributed.
Gently stir in 1 cup chocolate chips (milk or semi‑sweet).
Divide the batter evenly between the two prepared pans and smooth the tops.
Bake for 55–60 minutes, or until a toothpick inserted in the center comes out clean.
Let the loaves cool in the pans for about 10–15 minutes, then remove them from the pans and cool completely on a wire rack before slicing.