Chocolate-Zucchini Sheet Cake

1/2 cup (1 cube) margarine
1-3/4 cups sugar
1/2 cup buttermilk (or 1/4 cup sour cream and 1/4 cup milk)
1 tsp. cinnamon
1 tsp. vanilla
2 cups finely shredded zucchini (don't squeeze out water)
1/2 cup vegetable oil
2 eggs
1 tsp. baking soda
6 Tbl. cocoa powder
2-1/2 cups flour

Mix well and pour into greased and floured sheetcake pan.  Bake at 350 degrees for 20-25 min. until edges pull away from pan and it is set in the middle.

While cake is still warm, spread with frosting:
6 Tbl. cocoa
6 Tbl. milk (more, if needed)
1 tsp. vanilla
1 cube butter or margarine (1/2 cup)
1 lb. powdered sugar (3-1/2 - 4 cups)
Beat until smooth.  

This cake is even better the next day!