Preheat oven to 350 degrees. Lightly spray two 8X4" or 9x5" loaf pans; set aside.
In a large bowl whisk together the pumpkin, butter, oil, sugars, eggs and vanilla extract. Add zucchini and fold in with a spatula.
In a medium bowl whisk together the flour, baking soda, baking powder, salt, cinnamon, nutmeg, and cloves. Gradually fold into the wet ingredients along with chocolate or nuts (if desired), mixing just until combined.
Pour the batter evenly between the two prepared pans. Place in the oven and bake for 40-50 minutes (if using 9x5 pans) or 50-60 minutes (if using 8x4 pans) or until a cake tester inserted into the center comes out clean. Remove from oven and allow to cool in the pans for 15 minutes before removing and allowing to cool on a wire rack.
*Add 2/3 cup of your favorite mix-ins (chocolate or nuts) per loaf