Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch baking pan.
In a medium bowl, stir together the flour, sugar, cocoa, baking soda, baking powder, salt and cinnamon. Add the eggs and oil, mix well. Fold in the nuts and zucchini until they are evenly distributed. Pour into the prepared pan.
Bake for 50 to 60 minutes in the preheated oven, until a knife inserted into the center comes out clean. Cool cake completely before frosting with your favorite frosting.