Combine flour, cocoa, baking powder, soda, salt and cinnamon. Set aside. Beat together butter and sugar to smooth. Add eggs 1 at a time. Beat well. Stir in vanilla, orange rind and zucchini. Alternately stir in dry ingredients and milk. Add nuts.
Bake in greased and floured 10 inch tube pan or Bundt pan at 350 degrees about 1 hour till done. Cool in pan 15 minutes. Turn out. Drizzle with a powder sugar glaze.