Chocolate Mayonnaise Surprise Cake

2 Cups flour
2 Teaspoons baking soda
4 Tablespoons cocoa
1 Cup water
1 Cup sugar
1 Cup mayonnaise (not salad dressing)
1 Teaspoon Vanilla

- Sift flour, baking soda and cocoa. Set aside. In a large bowl, beat together the sugar, mayonnaise, water, and vanilla. Stir in the flour mixture until well blended and all ingredients are moistened. Pour batter into two greased and floured layer pans or a greased and floured 9x13 pan. Bake at 350°F for 30-35 minutes for layer pans or 30 minutes for an oblong pan. Cool and frost.