I think I remember seeing a Google link to a long list of gourmet cake flavours on CC and there was a pistachio cake recipe in there. It is the same link that has recipes from macsmom. Hoping someone has the link still to attach here. I believe this might be a sticky thread called "bride wants gourmet flavours for wedding cake" or something to that effect here under "RECIPES" forum.
Yes this thread ^^. I remember seeing a pistachio cake recipe in there. I have never tried it though because there isn't a demand for that flavour here but let us know if you do try it and how it goes. It sounds delicious already thinking about it.