Peel and grate three zucchinis and blot them dry with paper towels to remove some of the moisture. It should yield about 2 to 3 cups. Add them to a large mixing bowl. Then, add the remainder of the wet ingredients (eggs, oil, vanilla, and the brown and white sugar). Use a hand mixer to beat the wet ingredients on medium high for several minutes.
In a separate bowl, combine the dry ingredients (flour, baking powder, baking soda, and cocoa powder).
Continue beating the wet ingredients and slowly add the dry ingredients until they are well blended. Finally, fold in the chocolate chips.Use butter or Crisco or cooking spray to grease a Bundt cake pan. Use a spatula to transfer the batter from the bowl to the Bundt cake pan.Bake at 350° for about 45 minutes. The cake is done when you insert a large toothpick or kabob stick and it comes out clean. Allow the cake to cool, then, if desired, drizzle with glaze and immediately top with sprinkles. (To make the glaze, mix 1 cup powdered sugar, 2 Tablespoons milk, and 1/2 teaspoons of vanilla.)