Chocolate Zucchini Cake

1/2 cup butter, softened
1 1/2 cups sugar
3 eggs
1/2 c vegetable oil
3 tsp vanilla
1 3/4 cup all purpose flour
1/4 cup baking cocoa
2 tsp baking soda
1 tsp baking powder
1/2 tsp cinnamon
2 cups shredded zucchini
1 cup chopped walnuts (optional)
1/2 cup semi-sweet chocolate chips
In a mixing bowl, cream butter and sugar. Add eggs beating well. Beat in oil and vanilla. Combine the flour, cocoa, baking soda, baking powder, and cinnamon; gradually mix into wet ingredients. Fold in zucchini and walnuts if using. Spread into a greased 9X13 pan. Sprinkle with chocolate chips. Bake at 350 degrees for 30-35 minutes or until toothpick inserted in center comes out clean. Cool before slicing. Good with whipped cream or vanilla ice cream. No one will ever guess there is zucchini in it!