2 c. sifted flour
1 tsp. baking powder
1 tsp. baking soda
1/2 tsp. salt
1/4 c. cocoa
3/4 c. mayonnaise
1 c. sugar
1 c. water
1 tsp. vanilla

Sift first 5 ingredients together; set aside.

Combine mayo and sugar. Blend until smooth; add dry ingredients alternately with water and vanilla. Beat until smooth. Spoon into greased 9-inch square pan.