Old-Fashioned Chocolate Layer Cake America’s Test Kitchen

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Cakes, CakesChocolate

4 years ago Jeff the Chef

This is an excellent chocolate layer cake, with one of the silkiest, dreamiest frostings you can imagine. Gorgeous, unpretentions but super high-quality, homey and perfect … would make a kick-ass birthday cake. 

Makes 1 nine-inch, 2-layer cake

For the Cake

This recipe is from The Editors at America’s Test Kitchen. 2018. “Old-Fashioned Chocolate Cake.” In The Perfect Cake, 36-37. Boston, MA: Penguin Random House. I’ve paraphrased it and have provided my own notes.

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4 oz. unsweetened chocolate, chopped
4 oz. (½ cup) hot water
0.75 oz. (¼ cup) Dutch-processed cocoa
12.25 oz. (1¾ cups) sugar, divided
8.75 oz. (1¾ cups) AP flour
1½ tsp baking soda
1 tsp salt
8.5 oz. (1 cup) buttermilk
2 tsp vanilla extract
7 oz. (4 large) eggs, room temperature
2 oz. (2 large) egg whites, room temperature
6 oz. (12 Tbs) butter, softened

1. Prep two 9-inch cake pans with butter and flour. 
2. Whisk the chocolate, water, and cocoa in a double-boiler over barely simmering water until the chocolate has melted, about 2 minutes.

The water must truly be barely simmering; you want to heat it delicately.

3. Add ½-cup of the sugar, and continue to whisk until the mixture becomes thick and glossy, 1-2 minutes. Off heat. Set aside.
4. In a stand mixer with paddle attachment, combine the flour, baking soda, and salt, about 30 seconds on speed 2 (of 10). Transfer to a mixing bowl. Set aside.
5. To the buttermilk, add the vanilla. Set aside. Preheat oven to 350°F.
6. Switch to the whisk attachment, and whip the eggs, whites, and remaining sugar until it is able to produce thick ribbons, about 10 minutes on highest speed.
7. Switch to the paddle and add the chocolate mixture to the eggs, mixing until well combined, about 45 seconds on speed 4. Scrape the sides and bottom of the bowl thoroughly.
8. Beat in the butter, 1 Tablespoon at a time, about 10 seconds per addition.
9. Add the flour mixture in three additions on speed 2: flour then buttermilk, flour then buttermilk, and finally flour. Make sure each addition is incorporated before adding the next, about 10 seconds per. Thoroughly scrape the side and bottom of the bowl, then increase speed to 4 and mix once more, just for good measure, about 15 seconds. 
10. Give the batter a final, thorough stir by hand, using a flexible silicone spatula, making sure to get all the way to the bottom of the bowl.
11. Divide the batter between the pans (about 1 lb. 10 oz. per pan) and smooth the tops. Bake until cakes test clean with a few moist crumbs, about 27 minutes.
12. Cool 10 minutes on racks, then de-pan and cool thoroughly on racks.

For the Frosting

This recipe is from The Editors at America’s Test Kitchen. 2018. “Chocolate Frosting.” In The Perfect Cake, 399. Boston, MA: Penguin Random House. I’ve paraphrased it and have provided my own notes.

15 oz. (3¾ sticks) butter, softened
6 oz. (1½ cups) confectioners’ sugar
3 oz. (1 cup) Dutch-processed cocoa
Pinch of salt
12 oz. (1 cup) corn syrup
1½ tsp vanilla extract
12 oz. milk chocolate, chopped

1. Place the butter, sugar, and cocoa, and salt in a food processor, and process until well combined. 

My food processor won’t accommodate all of this. I had to make the frosting in two batches, and combine them by hand.

2. Process in the syrup and vanilla.
3. Melt the chocolate in the microwave, in 30-second bursts, stirring thoroughly in between bursts. Process it into the frosting. 

Ultimately, you want to melt the final remaining chunks via stirring, and not in the microwave. You should end up with melted chocolate that isn’t hot. If it is hot, let it cool. Process the chocolate into the butter mixture. 

You’ll have a bit more frosting than you need: eat it with a spoon.

This frosting has a mouse-like texture at first. Once it sets, the exterior is soft to the touch, but not tacky – yet the frosting stays creamy. It’s rich and chocolaty, but not dense and not fudgy.

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This cake is better at room temperature than it is straight from the fridge. I say that about a lot of cakes, but with this one, it’s even more true. At room temperature, the frosting compliments the cake in such a beautiful way. The cake is so deeply chocolatey, but its texture is light. The frosting – the milkiest, chocolatiest, creamiest, mousse-like stuff you can imagine – is shockingly not especially dense even if it is rich. The combination of the two leaves you awash in chocolate without knocking the breath out of you. It’s quite remarkable. 

I’m not as much a frosting fan as I am a cake fan, but I could eat this frosting all day long. You can swap out the milk chocolate for another chocolate, but you’ll change not just flavor, but texture. A darker chocolate will result in a fudgier frosting. 

Straight from the fridge, on the other hand, the cake is stiff and the frosting is blunt and overwhelming. (Not to the point that I wouldn’t eat it, mind you 😉 ) Fortunately a piece of cold cake, covered loosely in plastic wrap, returns to its most-perfect self in a short amount of time without drying out. In fact, I’ve been placing a slice on the counter and lettin it sit all day, as a reminder that if I make it through one more day of quarantine-online work, it will be my reward. 

You can expect this cake to be perfectly delicious for five days. On the sixth day, you’ll start to notice that the cake is drying out, but the frosting will still balance that out. That qualifies this as a good make-ahead cake. If you want to take out make-ahead insurance, aerate each layer with a toothpick before frosting the cake, and brush a quarter-cup of simple syrup onto each layer. 

I should add a paragraph here about cake storage. For long-term storage, I typically keep layer cakes refrigerated, in a tightly-sealed cake tote. The tote protects the cake from the refrigerator’s arid environment. Once the cake has been sliced, I use plastic wrap to seal the cut surface by pressing it up against that surface. The frosting doesn’t need protection; the only part of the cake that does is any exposed crumb.