As much a confection as it is cake, this dessert combines two layers of chocolate goodness — a dense and caky brownie and fudgy topping. The two elements merge when the cake is pulled from the oven and, while hot, is covered in a generous swath of frosting. As the frosting settles down, it melts onto the surface and melds with it.
Full-sugar Coke is a must here.
Make Ahead: Bake and serve within 2 days, or wrap the baked cake well and freeze; defrost completely before frosting.
Yield: (makes one 9-by-13-inch cake)
- For the cake
- 1/2 cup buttermilk
- 1 teaspoon baking soda
- 16 tablespoons (2 sticks) unsalted butter, cut into large chunks
- 1 cup Coca-Cola (do not use Diet Coke)
- 1/4 cup unsweetened cocoa powder (not Dutch process)
- 2 cups flour
- 2 cups granulated sugar, preferably superfine
- 1/2 teaspoon salt
- 2 large eggs
- 2 teaspoons vanilla extract
- For the frosting
- 3 3/4 cups plus 2 tablespoons confectioners' sugar
- 1/8 teaspoon salt
- 8 tablespoons (1 stick) unsalted butter, melted and cooled to tepid
- 2 ounces unsweetened chocolate, melted and cooled to tepid
- 1 1/4 teaspoons vanilla extract
- 6 tablespoons Coca-Cola, at room temperature (do not use Diet Coke)
For the cake: Preheat the oven to 400 degrees. Use cooking oil spray to lightly grease a 13 by 9 by 2-inch baking pan.
Whisk together the buttermilk and baking soda in a small nonreactive bowl. (The mixture should foam up a bit.)
Combine the butter, Coke and cocoa powder in a large saucepan over medium-high heat and bring to a boil.
Meanwhile, sift the flour with the granulated sugar and salt into the bowl of a stand mixer fitted with balloon-whisk attachment. Pour in the hot Coke mixture; beat on low speed for 2 to 3 minutes, until well incorporated. Add the eggs, vanilla extract and buttermilk-baking soda mixture, mixing well, to form a thin batter. Transfer to the prepared pan and bake for 25 to 27 minutes, or until the cake has risen and a tester inserted into the center comes out clean. Let the cake sit in the pan on a cooling rack for 5 minutes.
For the frosting: Sift together the confectioners' sugar and salt in the bowl of a stand mixer or handheld electric mixer.
Whisk together the butter and melted chocolate in a small bowl, until smooth. Add the vanilla extract. Pour the chocolate mixture over the confectioners' sugar-salt mixture, add the Coke and beat on low speed for 1 1/2 to 2 minutes or until well combined and smooth, stopping to scrape down the sides of the bowl often.
To use the frosting right away, carefully place dollops of it on top of the warm cake. Smooth them out with a small offset knife or spatula. The frosting will begin to melt down as you spread it, but it will firm up as it cools.
If you make the frosting in advance (while the cake is baking), press plastic wrap directly onto its surface.
From "ChocolateChocolate," by Lisa Yockelson (Wiley, 2005).
Tested by Bonnie S. Benwick.
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