DEVIL'S-FOOD CAKE WITH TOASTED-MARSHMALLOW FROSTING

Steps:

• Place oven rack in the middle position, and heat the oven to 350 degrees. Line 3 8-by-3-inch anodized-aluminum cake pans with parchment paper, and grease them.
• Combine butter and coffee in a 5-quart saucepan, and set over low heat to melt. Remove from heat, and whisk in the cocoa, chocolate, brown sugar, vanilla and salt, until there are no lumps of cocoa or unmelted chocolate. After mixing, add the eggs and yolks, and whisk well to combine. Sift flour and baking soda right into the pan, then whisk thoroughly to combine, making sure there are no pockets of flour. Divide batter among the three cake pans (about 23-24 ounces each).
• Bake for 30 minutes, or until the cakes are firm, but a light touch with a finger still leaves an impression, and a few crumbs cling to a toothpick inserted into the center of the cake.
• Set aside on a wire rack until the pans, and the cakes, are completely cool to the touch, about 90 minutes.
• Fill a 3-quart pot with 1 1/2 inches of water, and place over medium-low heat. In the bowl of a stand mixer, combine the egg whites, sugar, salt, cream of tartar and vanilla. Place the bowl over the steaming water bath, and use a spatula to stir and scrape down the bowl, keeping the mass moving over the steam for about 10 minutes, or until a digital thermometer inserted into the mixture reads 175 degrees.
• Place the bowl in the stand mixer with the whisk attachment, and whip on high speed until it quadruples in volume and turns thick and glossy, about 5 minutes.
• Loosen the sides of the cakes with a knife and invert them onto a wire rack. Peel away the parchment paper, then flip cakes right-side up again. Use a long serrated knife to evenly trim the puffy tops off the cakes (set these aside for snacking).
• Place one cake, cut-side up, onto a serving plate. Top with a cup of frosting, and spread it into an even layer with a small palette knife or the back of a spoon. Repeat with the second and third layers, placing these cut-side down. Finish the sides of the cake with remaining frosting, then lightly torch with a blowtorch, so the frosting turns golden brown.