Spread blue frosting in upper left corner. Pipe stars in blue field with reserved quarter cup vanilla frosting. Shortly before serving, place strawberries in seven rows to represent red stripes of flag. About 15 servings. * To sour milk: Use 2 teaspoons white vinegar plus milk to equal two third cup. Hershey's is a registered trademark of Hershey Foods Corporation. Recipe may be reprinted courtesy of the Hershey Kitchens.