I'm pretty sure most of the organic powdered sugars don't have cornstarch in them.

I make a buttercream type frosting and whip it extra long with my Kitchen Aid and it comes out pretty fluffy. I usually use real butter, but ghee would work fine or you could sub the palm shortening if you wanted. I use almond or rice milk in it and cocoa and powdered sugar. It's quite yummy and easy. (But don't ask for a recipe because I just throw stuff in there until it's the right consistency--then I end up with extra frosting sometimes, but hey, that's not a problem!)

Rachel