In a mixing bowl, cream butter, oil and sugar. Add everything else except zucchini and chocolate pieces. Stir well and add zucchini. Pour into greased 9 x 13 pan. Sprinkle with chocolate pieces (I use more than 1/2 c) and nuts if desired.
Bake in preheated oven:
325 45 min in GLASS pan
350 40 min in METAL pan
No frosting needed! Whipped cream is good on top, so is ice cream, but the cake can stand for itself!