what you need!
pack of ready to roll pastry
1 leek
diced chicken
can of condenced chicken soup
button mushrooms
salt and pepper
fry the chicken and leeks in a pan until cooked, add mushrooms, tin of soup and simmer. add salt and pepper to taste.
fill a pie dish with chicken mix
roll out pastry and top the mix
bake in oven at gas mark 5 for until pastry is golden brown
maybe not exactly what you want but try Jamie Olivers turkey and sweet leek pie (you can find it easily by googling) - without a doubt the best pie I've ever had and it's just as good with chicken
...ps. I just use pastry on the top and don't bother with the additions