Beat together butter, oil and sugar in a large bowl until light and fluffy.
Add the eggs, one at a time, beating well after each addition.
Blend in the flavorings.
Combine dry ingredients. Add to creamed mixture alternately with buttermilk, beating well after each addition.
Stir in the zucchini.
Pour into the prepared pan. Sprinkle with chocolate chips and nuts.
Bake about 50-55 minutes or until a wooden toothpick inserted in the center comes out clean; cool on a wire rack.
Notes
Note: If you have guests who cannot eat nuts, simply split the batter between two 8x8 or 8-inch round pans (one topped with nuts, one without) and reduce the baking time to 45 minutes.