From Simply in Season 

1 cup flour

¾ cup whole wheat flour

1/3 cup baking cocoa

½ tsp baking soda

½ tsp salt

2 to 3 cups grated/shredded zucchini

1 egg

¾ cup sugar

¾ cup brown sugar

½ cup plain yogurt

½ cup oil

1 tsp vanilla

½ to 1 cup semi-sweet chocolate chips

½ to 1 cup chopped nuts *optional

Preheat oven to 350F.

Combine in a large bowl the flours, cocoa, baking soda and salt.  Stir in the zucchini. 

In a separate bowl combine the egg, sugars, yogurt, oil and vanilla.  Stir into the zucchini mixture.  Spread into a greased 9 x 13 inch pan.  Sprinkle the chocolate chips and nuts, if using, on top of batter.  Bake for 35 – 40 minutes or until a toothpick inserted in the center comes out clean.