The filling is meant to remain very creamy and soft rather than becoming super firm. It will set somewhat in the refrigerator after chilling. A store-bought graham cracker crust works well, but you can also make your own or use an Oreo crust. For a pistachio ambrosia variation, add crushed pineapple, mini marshmallows, and chopped nuts.
Keyword easy pistachio pie, no bake pie, no bake pistachio pie, pistachio cream pie, pistachio pudding pie