Preheat oven to 350 degrees. Spray a 10 inch bundt pan with non-stick cooking spray. Dust the bundt pan with 2 T. cocoa powder. This will help keep the cake from sticking.
In a large mixing bowl, add butter and vegetable oil. Add in granulated and brown sugar. Mix on medium until incorporated.
Add in vanilla and eggs one at a time. Mix on medium and scrape down the sides of the bowl after each egg.
In a separate bowl, sift ⅓ cup of cocoa powder, baking powder, baking soda, and flour.
In a small bowl, add 2 T - 3 T. of sifted dry ingredients. Add in chocolate chips and stir to make sure the chips are covered. This will help keep the chocolate chips from sinking to the bottom.
Add the rest of the dry ingredients into the wet ingredients and mix on low until combined. Scrap down the sides and mix on medium for 30 seconds.
Stir in zucchini and floured milk chocolate chips into the batter.
Pour into the well cocoa powdered pan and spread evenly.
Place in the oven for 1 hour and 10 minutes or until done. Place a skewer in the center of the cake and if it comes out clean or with a few moist crumbs, it's done!
Remove from the oven and let cool for 15-20 minutes and turn out onto a cooling rack. Let the cake cool completely before pouring glaze on it.
Chocolate Glaze
In a mixing bowl, add in cocoa powder and corn syrup. Mix on low until incorporated.
Add in vanilla and half of the powdered sugar and mix on low. The glaze will start to get thick.
Add in the remaining powdered sugar and mix on low. If the glaze is too thick, add in the hot water. You may have to add more or less depending on how thick or thin you want the glaze.
Place cake onto a cake plate and pour glaze on cake. It's ready to eat!