You Need to Make Taylor Swift’s Flag Cake for 4th of July

— 9 tablespoons unsalted butter at room temperature

— 1 1/2 cups sugar

— 3 extra-large eggs at room temperature

— 1 cup sour cream at room temperature

— 3/4 teaspoon pure vanilla extract

— 1 1/2 cups flour

— 1/6 cup cornstarch

— 1/2 teaspoon kosher salt

— 1/2 teaspoon baking soda