Chocolate Cake

2 cups all purpose flour sifted
1 cup sugar
1/2 cup cocoa unsweetened
1 1/2 tsp. baking powder
1 tsp. baking soda
1 cup mayonnaise
1 cup water
1 tsp. vanilla
Butter and flour 13 by 9 by 2 pan. Mix and sift flour, sugar, 
cocoa, baking powder and baking soda in large mixing bowl. Stir in 
mayonnaise. Gradually stir in water and vanilla. Blend with an 
electric mixer until smooth. Pour into prepared pan. Bake at 350 
degrees for 35 to 40 minutes or until toothpick comes out clean. 
Cool completely. Frost if desired.