i think what u r looking for is a buttercream frosting for the cake..real easy to find and most bakeries i know of actually use it for many wedding cakes here is the recipe i use Buttercream Icing 1/2 cup solid vegetable shortening 1/2 teaspoon wilton Butter flavoring (extract) 4 cups of sifted powdered sugar 2 tablespoons of meringue powder 2 tablepoons of water or milk cream butter and shortening with electric mixer . Add butter flavoring, water and mix. add meringue powder and gradually add the sifted powdered sugar one cup at a time beating well on medium speed. Scrape sides and bottom of bowl often. if icing is too stiff you may add another tablespon of water..if still a little stiff ad another tablespoon of water but no more than that. keep icing covered with a damp cloth until ready to use, and refrigerate any leftover frosting up to 2 weeks.. re whip before using. yeild 3 cups please remember that if this is your first time making a wedding cake..the layers do not simply sit one on top of the other..they do have help in between each layer..depending upon what kind tiering you plan to do...if you are going for the stacked look of one on top of the other the best book i can possibly suggest to you for showing how to tier a wedding cake...will be any of the wiltos wedding cake books...it will show you how to tier the cakes..how to transport them..how to cut them and how many servings you will get out of the cake....keep in mind that the top layer of a wedding cake is not normally cut at the wedding recpetion but rather removed and is saved for the first wedding anniversary of the newly married couple.....when u go looking for a wiltons wedding cake book make sure u check it out to make sure allthe info u want is there...u may even find one or two that also have the recipe for the butter cream icing Have your friend taste test this and if it is the one she wants for her wedding cake you will need to make additional batches to cover the cake