Preheat oven to 350 degrees. Spray a bundt cake pan with baking spray or butter and flour the pan.
Whisk together flour, cocoa powder, baking powder, baking soda and salt in a medium bowl. In a large bowl, combine white and brown sugar with eggs, vanilla, oil, sour cream, and zucchini until mixed.
Stir the dry ingredients into the wet ingredients until almost combined. Fold in the chocolate chips.
Pour the batter into the prepared bundt pan. Bake for about 55-60 minutes or until a cake tester comes out with a few moist crumbs. Cool for about 20 minutes before inverting onto a cooling rack or serving platter. Once cooled completely, pour the glaze over the cake.
Melt the chocolate chips, butter and corn syrup together in a microwave-safe bowl at 30 second intervals, stirring after each interval, until combined.
You don't need to remove any excess moisture from the shredded zucchini. Just add it straight to the batter.
Be careful to not overmix the matter. Just mix until no streaks of flour are left and the chocolate chips are evenly incorporated.
Store, covered in an airtight container for about 3 days.