Preheat oven to 160ºC Grease 13x9-inch baking pan. Add 2-3 teaspoons flour to pan; gently tap side of pan to evenly coat bottom and side of pan with flour. Invert pan and gently tap bottom of pan to remove excess flour. Shred enough zucchini to yield 2 cups shredded zucchini; set aside. No need to peel zucchini before shredding. Beat together margarine, oil and sugar in large bowl until well blended. Add eggs, one at a time, beating well after each addition. Blend in flavorings. Combine dry ingredients in medium bowl. Add to margarine mixture alternately with buttermilk, beating well after each addition. Stir in zucchini. Pour into prepared pan. Sprinkle with nuts and chocolate chips. Bake 55 minutes or until wooden pick inserted in center comes out clean; cool on wire rack. Cut into squares. Frost with you favorite chocolate frosting, if desired. ----