This 7 ingredient Chocolate Mayonnaise Cake is moist, simple, and tastes divine! Enjoy it warm with a rich chocolate fudge sauce, chopped walnuts, and vanilla ice cream.
Preheat oven to 350°F. Grease a 9x9 inch baking pan.
Whisk the flour, sugar, cocoa powder, and baking soda together in medium mixing bowl. Add the water, mayonnaise, and vanilla and mix until evenly combined.
Pour batter into the prepared baking pan. Bake for 25-30 minutes or until toothpick comes out mostly clean.