2 c. cake flour
1 c. sugar
1 1/2 tsp. baking soda
1 1/2 tsp. baking powder
4 tbsp. cocoa
1 c. cold water
1 c. mayonnaise
1 tsp. vanilla

ICING:

1 c. sugar
1/4 c. cocoa
1/4 c. sweet milk
1/2 stick butter
1 tsp. vanilla

Sift the first 5 ingredients together into large bowl. Add the water, mayonnaise, and vanilla in order. Blend well. Pour into greased and floured sheet pan. Bake at 350 degrees for 35 minutes.

ICING: Melt butter in saucepan. Add sugar, cocoa, and milk. Boil 1 minute. Remove from heat and stir until partly cool. Add vanilla, pour over baked sheet cake and spread evenly.