Mix 1/2 cup starter, 1 cup water, 1/2 cup non-fat dry milk and 1 1/2 cups flour. Let stand 2 to 3 hours in warm place until bubbly and has sour milk odor.

In separate bowl, cream 1 cup sugar, 1/2 cup shortening, 1 teaspoon vanilla, 1 1/2 teaspoons soda, 1 teaspoon cinnamon and 1/2 teaspoon salt. Add 2 eggs, one at a time. Melt 3 squares semi sweet chocolate and add to creamed mixture. Combine sour dough and creamed mixtures, mix on low speed of mixer. Pour into greased and floured 9"x13" pan. Bake at 350 degrees for 25 to 30 minutes.