Blend sugar with cocoa in large mixing bowl or stand mixer. Add mayo & vanilla and mix. Combine flour and baking soda in separate bowl. Add dry ingredients along with water, alternating between additions. End with flour.
Bake at 350° for 40-50 minutes. When done, toothpick inserted in center will be clean. Makes 2 - 8" rounds or 9x13*.
"Nice with cream cheese frosting." ~Ann
*If baking 9 x 13 glass pan, cook about 30 minutes.