This is a very moist cake, the mayonnaise simply replaces eggs/oil!

3 cups flour
1 1/2 cups sugar
3 teaspoons baking soda
6 tablespoons cocoa powder
1 1/2 teaspoons vanilla
1 1/2 cups cold water
1 1/2 cups mayonnaise

Mix all ingredients in order given.
Bake at 350 degrees for 30 minutes.
Cool and frost!  My family likes Peanut Butter Frosting best.
Make vanilla butter frosting and add about 1/2 cup peanut butter.