In a medium bowl, whisk together the flour, cocoa, baking powder, baking soda, salt, and cinnamon. Set aside.
In a large bowl, with mixer, beat butter and sugar until creamy. Add eggs, one at a time, and beat after each one. Add vanilla and orange extracts, orange rind, and drained zucchini. Beat on medium to blend together.
Mix in dry ingredients alternating with buttermilk. Stir until well blended. If using nuts, stir them in now. Pour batter into prepared bundt or tube pan.
Bake in preheated 325 degree oven 55-60 minutes or until cake springs back when touched. Cool on wire rack 8-10 minutes then turn out on cake plate to finish cooling.
Cocoa Orange Frosting: In a medium bowl, cream butter and powered sugar. Add cocoa and mix until well blended. Beat in milk, orange rind, and both extracts. Spread on plated cool cake.