More on sugar, the powdered variety

Ditto to the previous post: There's no reason at all to add powdered sugar atop anything. Simply not necessary!

And further, when making a buttercream frosting, is almost obscene how much sugar the general recipe calls for, i.e., one pound confectioners sugar (a small box) to often approximately 12 ounces of butter (and do not use shortening -- don't even get me started!). Stop right there. In this case, cream your butter first, and then add confectioners sugar slowly; 1/2 to 3/4 pound of sugar here is usually fine.

Extra credit tip: Don't pile on the frosting. It's called cake for a reason, and the frosting -- well, that's just the icing on the cake.