Adding the look of a flag to the top of the cake can be done in a variety of ways. It can be done by using red, white and blue frosting and simply piping it on top. Or you can actually add food coloring to the cake and make a layered cake that is red, white and blue when you cut into it. Personally, this recipe is my favorite because it uses a light Cool Whip topping combined with fruit and is much easier and quicker than the other two options.