Years ago my family started making this cake as dessert on St. Patrick’s day. It’s one of the moistest, densest chocolate cake recipes that I know of. It isn’t very sweet but is moist and amazing. The secret is the use of mayonnaise in the place of oil and eggs. It may sound odd, but it is great. The cake recipe originally comes from the Macaroni Grill. They serve it with a rich, heavy ganache, but I like to top it with one of my favorite icing recipes.
The icing recipe comes with an inside joke. Years ago, my mother had made some chocolate cake with this frosting. A neighborhood friend tried it and begged for the recipe. The frosting is mellow, smooth, luscious, and not too sweet. My mother gave her the recipe and she attempted to make it the next day. The recipe involves using granulated sugar instead of powdered sugar (which is common in many buttercreams). While the neighbor was making the frosting, a nosy (know-it-all) neighbor happened to visit. When the nosy neighbor saw what my mother’s friend was doing, she exclaimed “it’s impossible to make frosting with granulated sugar!”. She talked my mom’s friend into throwing the entire finished batch out. Since then, this frosting has been known as Impossible Frosting.
For the cake:
2 1/4 cups – Cake flour
1 Tbsp. – Baking soda
1/2 cup – Dutch processed cocoa powder
1 3/4 cups – Granulated sugar
1 3/4 cups – Mayonnaise
1 3/4 cups – Cold brewed coffee (I use Pero since I don’t drink coffee)
1/2 Tbsp. – Vanilla extract
For the frosting:
5 Tbsp. – All-purpose flour
1 cup – Milk
1 cup – Granulated sugar
1/2 cup – shortening
1/2 cup – butter
1 tsp. – vanilla or almond extract
Preheat oven to 350 degrees.
Sift flour, baking soda, cocoa, and sugar together until smooth.
Make sure that the coffee is cool to avoid an early reaction to the baking soda, then add it to the flour, cocoa mixture, along with the rest of the ingredients.
Lightly mix until well incorporated but not over mixed then add to a greased, floured 13×9 inch baking pan.
Bake for 35 minutes or until a toothpick comes out clean. Let cool.
Now to make the impossible frosting, add the flour and milk to a small sauce pan. Bring to a boil, stirring constantly until the mixture is thickened. Allow to cool fully.
In a large stand mixing bowl, cream together the sugar, shortening, and butter. Beat 8 minutes or until very fluffy. Add the extract (I prefer the almond extract) and several drops of food coloring. Beat 4 more minutes.
Add the cooled flour mixture and beat 4 more minutes. Frost in an even layer on the cake.