2 sticks (1 cup) unsalted butter, softened
2 cups sugar
4 large eggs at room temperature
2 tsp pure vanilla extract
3 2/3 cups all-purpose flour plus 1/3 cup cornstarch*
2 tsp baking powder
1 tsp baking soda
1 tsp table salt
2 cups buttermilk, well-shaken
8-ounce block cream cheese, at room temperature
1 stick (1/2 cup) butter, at room temperature
1 teaspoon vanilla extract
1 to 3 cups powdered sugar, depending on preference
Powdered sugar sprinkles
1 cup blueberries, very dry
3 cups raspberries, very dry or strawberries!
*You can substitute 4 cups of cake flour if you don’t have cornstarch
Preheat oven to 350°F. Butter a 9×13-inch baking pan and line the bottom with a rectangle of parchment paper, then butter the parchment. Now is a good time to take out the cream cheese and butter for the frosting so it can come to room temperature while you work.
1. Beat butter and sugar together in a large bowl until light and fluffy. Add eggs one by one . Add vanilla extract.
2. Measure out the flour, cornstarch, baking powder, baking soda and table salt into a medium-sized bowl, then put half into a sifter. Sift the dry mixture into the wet ingredients. Mix until just combined. Slowly add buttermilk, then sift in the other half dry ingredients and mix until combined.
3. Pour batter in prepared pan. Bake until golden and a wooden pick inserted in center of cake comes out clean, about 40-50 minutes. Mine got rather domed on top, which I was fine with, but if you want it to really look like a flag, you can shave off the top with a serrated knife once it comes out and has cooled. In addition, if you don’t have a perfectly rectangular pan with sharp corners (as I didn’t), you can cut off the four edges to give it a more uniform, rectangular feel.
Beat cream cheese and butter together until fluffy; I did it by hand since I don’t have a mixer and I start with smooshing the cream cheese with a spatula to get it smooth, then add the softened butter. This way the cream cheese doesn’t get lumpy. Add the vanilla, mix, then add the first cup of powdered sugar, and beat it until combined. I recommend using a sifter when putting in the powdered sugar, so that clumps don’t get in. I only used one cup of powdered sugar, though most people would use two cups. If you like really sweet frosting, use three cups! That will also make the frosting more stiff and white, which you may prefer with your decorating. Taste along the way as you add it, so you know how sweet you’re making it (also a great excuse to eat frosting).
Assemble the cake
1. After letting the cake cool completely, dollop on your cream cheese frosting. Smooth to the edges of the cake evenly.
2. For the stars section of the flag, space your blueberries apart enough that another could fit between them. I did five down and eight across, roughly, but that depends on the size of your blueberries. After setting down your spaced out rows, sift powdered sugar over all of them. Then, fill in the rest of the space with blueberries that will remain blue.
3. For the stripes, you can do raspberries and use the same tactic as the blueberries (that’s how the original recipe went) by spacing the stripes out, dusting them with powdered sugar, and then filling in the rest with plain raspberries. I love strawberries and already had a plethora so I decided to layer strawberries for the stripes and let the frosting stand in as the white stripes. Either way works! Be creative.