Chocolate-Marshmallow Cake

This is an old-school jelly roll style chocolate cake leaning hot-milk-cake territory: whole eggs beaten until thick and lemon-colored form the entire leavening backbone alongside a teaspoon of baking powder. The batter spreads thin into a sheet pan and bakes in about 12 minutes, yielding a fine, cocoa-forward sponge.

The drama comes from the frosting. Egg whites, sugar, cream of tartar, and corn syrup get whipped over heat into a glossy seven-minute frosting, then cut marshmallows fold in and nearly dissolve, doubling down on the cloud-soft, stretchy texture. Spread thick over the cooled cake, it looks like a cumulus bank over a chocolate field.

Pro Tips

• Beat the eggs until they triple in volume and fall in ribbons from the beater. This foam carries the whole cake, and underbeating here gives you a dense, flat sponge.
• Line the pan with foil and grease generously. The foil lets you peel the entire cake off in one piece, which is important when the sheet is this thin and fragile.
• Invert onto a powdered sugar-dusted towel the moment it comes out of the oven. Waiting lets steam condense on the surface and the cake will stick to the foil.
• Make the marshmallow frosting only when the cake is fully cool. The frosting weeps if it hits warm cake, and you lose that glossy peak structure.

Variations

• Sandwich two stacked cakes with chocolate ganache between for a layer cake version.
• Toast the marshmallow frosting with a kitchen torch for full s’mores effect.
• Fold crushed graham crackers and miniature chocolate chips into the frosting for full-on s’mores flavor.