In a mixing bowl, beat the butter, oil, and sugar. Add the eggs, buttermilk and vanilla; mix well. Combine the flour, cocoa, baking soda, baking powder, salt, cinnamon, cloves and allspice; gradually add to creamed mixture. Mix together well. Stir in zucchini.
Spread batter into a greased 13 x 9 inch baking pan. Sprinkle with nuts and mini chocolate chips. Bake at 350º for 35 to 40 minutes or until a toothpick inserted near the center comes out clean. Cool on wire rack.