Cake came out fabulous, although I did alter a few things. I omitted the egg yolks, and use large egg whites (since it is a white cake), and I melted my chocolate and butter over a double boiler and used real white chocolate, not bakers chocolate. I also only used about 3/4 stick of butter rather than a whole one. Extra vanilla, which I put in everything I cook :)
I made this recipe as a 3 tier cake for a wedding, didn't use their frosting, made a home made butterceam instead and then fresh raspberries on top. My suggestion to those using the frosting recipe, would be to add everything they say, then just add 1/2-1 cup of confectioners sugar. Easy as that :) keep adding sugar until it reaches the consistency you'd like :)
I never ever make box cakes, but this one was suggested by the bride, and it came out wonderful.