Preheat the oven to 350 ° F.
Grease or spray a 13x9-inch oblong pan.
With an electric mixer on medium speed, cream the butter and sugar together.
Add the oil, eggs, and vanilla extract and mix well.
In a small bowl, mix the flour, baking cocoa, baking soda, baking powder, cinnamon and ground cloves. Add it to the creamed mixture.
Add the buttermilk. Mix well.
Add the zucchini, mix well on low speed. Scrape the sides of the bowl.
Pour the mixture into the prepared pan.
Sprinkle the chocolate chips evenly over the batter.
Bake at 350° F. for 25-30 minutes. Test for doneness with a cake tester inserted in the middle. Do not overbake.
Remove the pan to a wire rack to cool. (Optional: Top with a vanilla or chocolate glaze.) Cut into squares.