I would like to make a cake with pistachio buttercream.Do you have recipe?

I would just add Pistachio pudding mix to whatever buttercream you normally use (add to taste) in place of some of the powdered sugar, or if you use a meringue based one, just add until it has the taste you want, maybe add a touch of green color and chopped pistachios too for effect. Good luck, let us know how it turns out!

you can add some lor-ann pistachio flavoring!

Thanks, I'll try.