“Toasted marshmallow makes my heart race. It’s the ultimate indulgence to have an entire cake coated in toasted marshmallow frosting. Chocolate cake and crushed graham crackers just complete the s’more trifecta. Frost Basic Three-Layer Chocolate Cake (recipe follows) with Marshmallow Meringue Frosting (recipe follows), sprinkling crushed graham crackers between each frosted layer. To serve, sprinkle the cake with big chunks of graham cracker. Toast the meringue by grazing the topping with the flame of a kitchen torch until it is golden brown. Alternately, you can toast the cake in a 375-degree oven for about 4 minutes.” — Joy Wilson, author of Homemade Decadence.
Note: Keep an eye on the cake. It toasts quickly.
Put oven racks in the center and upper third of the oven and preheat the oven to 350 degrees. Grease and flour three 9-inch round baking pans.
In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, salt, and instant espresso powder if using.
In the bowl of an electric mixer fitted with a paddle attachment, beat the butter and sugars together on medium speed until light and fluffy, 3 to 4 minutes. Add the eggs one at a time, beating for 1 minute after each addition. Beat in the vanilla extract. Reduce the mixer speed to low, add half of the flour mixture, and beat until the flour mixture is incorporated. Add the buttermilk in a slow stream and beat until thoroughly combined. Add the remaining flour mixture and beat until just combined. Remove the bowl from the mixer and finish stirring with a spatula. Divide the batter among the 3 prepared cake pans.
Bake until golden brown on top and a wooden pick inserted in the center comes out clean, 20 to 25 minutes. Let cool in the pans for 20 minutes before inverting onto wire racks to cool completely before frosting.
If you’re not frosting the cake right away, double-wrap in plastic wrap and store in the freezer. Cake layers will stay freshest for up to 7 days in the freezer. When ready to frost, remove from the freezer, unwrap, and frost frozen!
In a large, heat-proof bowl, whisk together the egg whites, corn syrup, sugar, and salt. Put the bowl over a saucepan of simmering water, making sure that the bottom of the bowl does not touch the simmering water. Whisk the mixture as it heats and cook until the sugar dissolves, about 5 minutes.
Transfer the mixture to the bowl of an electric mixer fitted with the whisk attachment. Beat the egg whites on high speed until stiff peaks form, about 5 minutes. The mixture will be fluffy and glossy and look like melted marshmallows. It’ll be sticky, too. Beat in the vanilla. Frost cake just after frosting is made.