Magnolia Bakery's Vanilla Birthday Cake and Frosting

Recipe originally found here

The cake was very very good, and I will for sure make it again. The frosting, through no fault of the recipe, didn't turn out so great. I think the problem was that I substituted for powdered sugar (from here). The frosting turned out grainy and just plain yuck. I also added 2t of raspberry extract, just to try it out. I definitely got some of that flavor, but BAJ said the frosting was flavorless.

Picture of my poor sad wimpy frosted cuppie coming soon.