1Heat oven to 350°F. Generously spray 2 (8x4-inch) loaf pans with cooking spray.
2In large bowl, beat cake mix, eggs, zucchini, vanilla, cinnamon, melted butter and granulated sugar with electric mixer on medium speed until blended, or mix with spoon. Stir in chocolate chips. Divide batter between pans.
3Bake 45 to 50 minutes or until center of loaf springs back when touched. Run knife around sides of pans to loosen; cool completely, about 2 hours. Remove from pans to cutting board. Sprinkle with powdered sugar. Cut each loaf into 8 slices.