Cook veggies according to package directions and drain.
In medium saucepan, cook onions and mushrooms in butter until tender but no brown. Stir in flour, salt, sage and pepper.
Add water, milk and chicken bouillon granules all at once. Cook and stir until thickened and bubbly.
Cook and stir 1-2 minutes more. Stir in drained veggies, chicken pimento, and parsley. Heat until bubbly.
Line the bottom of a greased pie plate with one pie crust.
Pour chicken mixture into dish.
Place the 2nd pie crust on top of the chicken mixture; cut slits in top for steam.
Bake at 450 for 25 minutes or until crust is golden brown. A chilled casserole will take much longer.