Chocolate Mayonnaise Cake with Marshmallow Frosting
Rich and chocolatey cake topped with a light as air marshmallow frosting - that tastes like melted marshmallows! Such an irresistible cake and flavor combination!
Preheat oven to 350 degrees F. Spray a 13 by 9-inch baking dish with non-stick cooking spray.
In a medium mixing bowl whisk together flour, cocoa powder, baking soda and baking powder for 20 seconds, set aside.
In a separate large mixing bowl, using an electric hand mixer set on high speed, beat eggs, sugar and vanilla for 3 minutes. Blend in mayonnaise.
Mix half of the flour mixture into the sugar/mayonnaise mixture, mix in the water then mix in remaining flour mixture. Pour into prepared pan.
Bake in preheated oven until toothpick inserted into center comes out clean, about 34 - 38 minutes. Let cool completely on a wire rack (I like to cover about halfway through to seal in moisture).
Frost completely cooled cake with marshmallow frosting then top with chocolate shavings.
For the frosting:
Fill a large saucepan with about 1 1/2-inches of water and bring to a simmer. Add egg whites, granulated sugar and cream of tartar to a heat proof bowl of an electric stand mixer.
Set bowl over saucepan (make sure it doesn't touch water) and heat mixture, whisking constantly until it's very warm (I let mine get to 150 degrees F), about 3 - 4 minutes.
Remove from heat and transfer bowl to electric stand mixer fitted with a whisk attachment.
Beat mixture beginning on low and increasing to high speed until stiff glossy peaks form, about 5 - 7 minutes.
Pour in vanilla during the last 10 seconds of mixing. For best results serve within a few hours of preparing - keep frosting cold.
Notes
If even the tiniest bit of egg yolk gets into the marshmallow frosting, it won't whip up properly. So be really careful when separating the yolks from the whites.