Skill Level

Intermediate

Yields

Serves: 20 to 24 people

Nutritional Information (per serving 1 of 22)

Calories: 657
Total Fat: 41 g
Saturated Fat: 24 g
Carbohydrates: 69 g
Dietary Fiber: 2 g
Sugar: 51 g
Protein: 6 g
Cholesterol: 164 mg
Sodium: 270 mg

Time

Total Time: 1 hour 15 minutes
Preparation Time: 45 minutes
Baking Time: 30 minutes

Ingredients

18 tablespoons (2 1/4 sticks) unsalted butter, softened

3 cups sugar

6 extra-large eggs, at room temperature

1 cup sour cream, at room temperature

1 1/2 teaspoons pure vanilla extract

3 cups all-purpose flour

1/3 cup cornstarch

1 teaspoon kosher salt

1 teaspoon baking soda

For the frosting:

1 pound (4 sticks) unsalted butter, softened

1 1/2 pounds cream cheese, softened

1 pound sifted confectioners' sugar

1 1/2 teaspoons pure vanilla extract

For decorating:

2 half-pints blueberries

3 half-pints raspberries

Instructions

Preheat your oven to 350F (175C).

Grease and flour an 18 x 13 x 1 1/2-inch sheet pan.

In the bowl of an electric mixer fitted with the paddle attachment, beat the butter and sugar on high until light and fluffy; reduce to medium and add the eggs two at a time. Mix in the sour cream and vanilla, scraping the bowl until smooth.

In a separate bowl, sift together the flour, cornstarch, salt, and baking soda. On low speed, gradually add the dry mixture to the wet ingredients until just combined. Pour batter into the prepared pan, spread evenly, and bake on the center rack for 20 to 30 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool to room temperature.

To make the frosting, beat the butter, cream cheese, confectioners' sugar, and vanilla in an electric mixer fitted with the paddle attachment until smooth and creamy.

Spread about three-quarters of the frosting over the cooled cake. Use a toothpick to lightly mark the outline of a flag across the top of the cake, and fill the top-left "star" area with blueberries.

Create two rows of raspberries to form the first red stripe, then pipe two rows of white frosting beneath them using the remaining frosting in a pastry bag fitted with a star tip. Alternate rows of raspberries and piped frosting until the flag pattern is complete.

Pipe small dollops of frosting on the blueberries to mimic stars.

Serve the cake directly from the pan; if you prefer to remove it before frosting, line the pan with parchment before greasing and flouring.