Fluffy White (Flag) Cake with Buttercream
Serves: About 60
 
This recipe is based on many, many I’ve tried—but all roads seem to lead back to Cook’s Illustrated white cake method. The cake is the lightest, fluffiest of its kind for a homemade cake, and the flavor is excellent.
Ingredients
  • For the cake:
  • 5 large egg whites, room temperature
  • 1 whole egg, room temperature
  • 1 cup whole milk, room temperature, divided
  • 2 teaspoons pure vanilla extract or pure lemon extract
  • 3 cups cake flour, sifted
  • 2 cups sugar
  • 1 tablespoons + 1 teaspoon fresh baking powder
  • ½ teaspoon salt
  • 12 tablespoons unsalted butter, very cold and cut into ½ tablespoon pieces
  • For the buttercream:
  • 1 lb. unsalted butter, softened and cut into 1-inch pieces
  • 1 lb. cream cheese, softened
  • 6 cups confectioners’ sugar, sifted
  • 3-5 tablespoons milk or heavy cream
  • 2 teaspoons pure vanilla or lemon extract
  • pinch of salt
  • For the flag decoration:
  • 5 pints raspberries
  • 1 pint blueberries
Instructions
  1. For the cake:
  2. Preheat the oven to 350°F. Grease and flour one 18x13x1½-inch pan (pan size can vary, just fill to about halfway up the sides of the pan, or less, and use batter in more than one pan if needed).
  3. In a medium bowl or large measuring cup, whisk the egg whites, whole egg, ¼ cup of the milk, and vanilla. Set this aside.
  4. In the bowl of an electric mixer, whisk the dry ingredients until combined. Using the paddle attachment on low speed, add the butter one piece at a time until the mixture is a fine crumbly texture. Add the remaining milk and continue to mix on low for about five minutes, stopping to scrape down the sides of the bowl occasionally. Add the egg mixture in 3 separate batches, mixing on low until light and fluffy, another 3-5 minutes. Scrape and fold the batter.
  5. Scrape the batter into the pan and spread it evenly. Bake until the cake is spongy in the center when touched with the tip of your fingers, or until a cake tester comes out with a few crumbs when inserted in the center, about 30 minutes. Be very careful not to overbake! Start checking for donness at 20 minutes.
  6. If you’re serving the cake from the pan, cool the cake in the pan on a rack. Otherwise, let the cake rest for 10 minutes, loosen the sides with a knife, then flip the cake out carefully onto the back of a sheet pan or other large surface for serving. Frost the cake when it is completely cool.
  7. For the buttercream:
  8. In an electric mixer fitted with the paddle attachment beat the butter and cream cheese on medium speed until it is light and fluffy, about 5 minutes. Add the confectioners’ sugar in several batches (to avoid a big poof when you turn on the mixer) and mix on low to incorporate. Add the vanilla or other flavoring and the salt, and then add a tablespoon of milk with each addition of confectioner’s sugar—but only enough milk to make the buttercream smooth; be careful not to add too much liquid. The buttercream should be thick and spreadable, but still holding its shape.
  9. The buttercream can be made several days in advance and stored in an airtight container in the refrigerator. Bring to room temperature before using.
  10. To decorate the cake, smooth a couple of cups of the buttercream over the top (and sides if it's turned out of the pan. Or not! Exposed sides are lovely too). Score the cake with a knife for the stars and stripes as a guide. Use a piping bag fitted with a flower tip, or simply fill a gallon-sized plastic ziplock bag with buttercream, and snip off the end. Pipe rosettes or simple large dots for the stars in the upper left corner, and top each with a blueberry. Make four double horizontal rows of raspberries for the strips, piping icing decoratively in between. Beautiful! Delicious!
Recipe by Rose Water & Orange Blossoms at https://www.maureenabood.com/fluffy-white-flag-cake-with-buttercream-an-adventure/