- 2 1/4 sticks unsalted butter, at room temperature (I used 1/2 cup butter flavor Crisco at high altitude)
- 3 cups sugar (cut down to 2 3/4 at high altitude)
- 6 extra-large eggs, at room temperature
- 1 cup Sour Cream, at room temperature
- 1 1/2 teaspoons Mexican vanilla or pure vanilla extract
- 3 cups unbleached flour(I like King Arthur or Pillsbury)
- 1/3 cup cornstarch
- 1 teaspoon Kosher salt
- 1 teaspoon baking powder
For the Icing:
- 1 pound(4 sticks) unsalted butter, at room temperature
- 3 -8oz. pkgs. cream cheese, at room temperature
- 1 pound powdered sugar( I added another 1/2 cup or so, thought it was too runny)
- 1 1/2 teaspoons Mexican vanilla or vanilla extract
- 2 half-pints blueberries
- 3 half pints raspberries
Preheat oven to 350 degrees. Butter and flour an 18x12x1 1/2 inch cake sheet pan(see above).
Cream the butter and sugar in the bowl of an electric mixer fitted with the paddle attachment on high speed until light and fluffy. On medium speed, add the eggs one at a time, then add the sour cream and vanilla. Scrape down the sides and stir until smooth.
Sift together the flour, cornstarch, salt and baking soda in a bowl. With the mixer on low speed, add the flour mixture to the butter mixture until just combined. Pour into the prepared pan. Smooth the top with a spatula. Bake in the center of the oven for 20-30 minutes, until a toothpick comes out clean. Cool to room temperature.
For the icing, combine the butter, cream cheese, powdered sugar and vanilla in the bowl of an electric mixer fitted with the paddle attachment, mixing until smooth. Spread 3/4 of the icing on the top of the cooled sheet cake. Outline the flag on the top of the cake with a toothpick. Fill the upper left corner with blueberries. Place 2 rows of raspberries across the top of the cake like a red stripe. Put the remaining icing in a pastry bag with lg. star tip and pipe 2 rows of icing below raspberiies. Alternate rows of icing with raspberries until flag is complete. Pipe stars on top of the blueberries. WA-la a 4th of July centerpiece!