Chocolate Mayonnaise Cake

Ingredients:

Sift together:

2 cups flour
1 cup sugar
1/2 cup cocoa
1 1/2 tsp baking powder
1 1/2 tsp baking soda

Add:
1 cup (+~2 tbsp) ice water
2 tsp (+) real vanilla extract

When mixed thoroughly, fold in:

1 cup real mayonnaise

Instructions:

If you're using a mixer, fold the mayonnaise in by hand. Stir just till
mixed; do not over beat. Pour into a greased and floured (or Baker's
Joy'ed) 13x9x2 pan and bake 30 minutes at 350 F. Cake is done when it starts to pull away from the sides of the pan and the top starts to crack; you can also use a toothpick test; do not overcook. Cool five
minutes before removing from the pan. 

Frost with canned frosting or homemade butter frosting:

1/2 stick butter
1 lb powdered sugar
(dash salt)
1/2 cup cocoa (optional)
2 tbsp (+) milk
1 tsp (+) vanilla

Instructions:

Cream butter, 1/2 sugar, and salt. Add cocoa and 1 tbsp milk. Cream. 
Add sugar and milk till the consistency is right and then beat at mixer's highest speed. Frost cake immediately.