For a quick and easy one, i buy the pastry (jus-rol) and lay it out in a pie tin. Add layers of cooked chicken...sometimes off the cacrcase off the sunday roast gives enough, and mushrooms. Chuck in some softened onions if you want too then i use two small tins of Campbells condensed "cream of chicken and white wine" soup.
Put the top on and chuck in oven until the pastry is cooked. (about 25-30 mins.)