Preheat oven to 350°F. Generously spray with baking spray and lightly flour two 8”x4” loaf pans. Or spray baking spray and lay parchment paper on the bottom and up the sides being sure to have enough to overhang
Grate the zucchini. Shred it on the large holes of a box grater and measure 2 packed cups. Place the grated zucchini between paper towel to drain. Gently press any excess moisture from the grated zucchini and set aside.
In a large bowl, add cake mix, eggs, vanilla, cinnamon, melted butter and granulated sugar. Using an electric mixer beat on medium speed until blended, or mix with a large spatula until blended.
Stir in the zucchini until well combined. Stir in chocolate chips.
Divide batter between loaf pans. Place both loaves on a baking sheet pan.
Bake for 45 to 50 minutes or until the center of the loaf springs back when touched or when the toothpick placed in the center comes out clean. Run the knife around the sides of the pans to loosen; cool completely, about 1 hour.
Remove zucchini loaves to the cutting board. Sprinkle top with powdered sugar. Slice each loaf into 8 slices.