2-3tablespoonsmilk, cream, or half-and-half -- to make a spreadable frosting
Instructions
Making the cake:
Preheat the oven to 350°F. Grease a 9x13 inch baking dish with cooking spray.
Whisk together the flour, cocoa, baking powder, baking soda, and salt in a medium bowl. Set aside.
In a large bowl (stand mixer or a bowl using electric beaters), beat the egg and sugar for 2 minutes. Add in mayonnaise, vanilla and water and continue to beat.
Next, slowly add the dry ingredients (flour, cocoa, baking powder, baking soda, and salt) a little at a time, mixing as you go. Scrape down the sides as you mix the batter.
Pour the cake batter into the prepared pan. Bake for 30-35 minutes. Check with a toothpick, in the middle of the cake, if it comes out clean (then the cake is done). Transfer the cake to a wire rack and let cool completely before frosting, otherwise the frosting will stick to the cake while spreading.
Making the Chocolate (coffee) Frosting:
In a large bowl, beat the butter and confectioners' sugar at low to high speed until light and fluffy, for 2-3 minutes. Next, add in the cocoa, cold coffee, and vanilla. As it thickens up, slowly add in the milk one tablespoon at a time until desired thickness for spreading on the cake. The amount of milk depends on how thick or creamy you like your frosting.
Spread the frosting on top of the cake.
Notes
Sandy's Tips
You can use any kind of full-fat, unflavored mayonnaise in this recipe. Do not use Miracle Whip; it will not have the same flavor.
Don’t overmix the cake batter - only mix it as needed to blend in all the ingredients.
You can use cream or half-and-half cream in the icing instead of milk.
You can make the icing while the cake cools. Just leave it on the counter so it stays soft enough for spreading.
Every oven is different: Check for doneness before removing from the oven.