It’s easy to create a supremely fluffy layer cake with additives. Box mixes are engineered to produce a cake with ultralight texture. But most cakes made from entirely natural ingredients are either unpleasantly dense or too fragile to support layers of frosting. We set out to change that.
Chiffon cakes are especially weightless, springy, and moist. But unlike butter cakes, they are too light to stand up to a serious slathering of frosting. We decided to blend the two types of cake. Adapting a chiffon technique (using a large quantity of whipped egg whites to get a high volume and light texture) to combine the ingredients from our butter cake recipe worked beautifully, creating a light, porous cake that was hefty enough to hold the frosting’s weight. But the cake lacked moistness and some tenderness. Using a combination of fats (10 tablespoons of butter plus 3 tablespoons of vegetable oil) kept the butter flavor intact while improving the moistness of the cake. For extra tenderness, we increased the sugar and substituted buttermilk for milk. The buttermilk not only introduced a new flavor dimension, but also allowed us to replace some of the baking powder with a little baking soda to ensure an even rise.
For the chocolate frosting, we used a combination of milk chocolate and cocoa powder for big flavor and combined the classic ingredients for a quick frosting—softened butter and confectioners’ sugar—in a food processor to create a billowy frosting without the usual gritty texture.
This cake can be assembled and refrigerated for up to 1 day. Bring to room temperature before serving. If you prefer, the cooled cakes can be wrapped tightly in plastic wrap and kept at room temperature for up to 1 day. Wrapped tightly in plastic, then aluminum foil, cakes can be frozen for up to 1 month. Defrost cakes at room temperature before unwrapping and frosting. As for the frosting, it can be kept at room temperature for up to 3 hours before frosting cake or refrigerated for up to 3 days. If refrigerated, let stand at room temperature for 1 hour before using.