Preheat oven to 350º
Grease 13 x 9 baking dish.
Place zucchini in a colander; sprinkle with salt. Set aside to drain.
Mix together flour, cocoa powder, aking soda, and cinnamon.
Mix together eggs, sugar, and orange peel; stir in oil.
Stir flour mixture into egg mixture until moistened.
Press zucchini with paper towles to extract moisture. Stir zucchini into batter. Scrape into prepared pan.
Bake 20-25 minutes; transfer pan to wire rack to cool completely.
Mix together: 2 cups powdered sugar, 1/4 cup butter, softened, 2 tablespoons orange juice, 1 teaspoon grated orange peel.
Spread icing on cooled cake.