Preheat oven to 350 F. Lightly spray a 9 inch pie pan with baking spray.
Mix flour, baking powder, and salt together. Mash in butter with a fork until there are only pea-sized pieces. Stir in milk and mix to form the dough.
Divide the dough into roughly half, one part slightly larger than the other for the bottom. Roll out the larger portion of dough into an even circle big enough for the pie pan and place in pan.
In a bowl, whisk together the milk, cream of chicken soup, chicken gravy mix, parsley, and pepper.
In the pie shell, pour in half of the chopped chicken and thawed veggies.
Pour in half of the gravy mixture, then layer in the other half of the chicken and veggies and the last of the gravy.
Roll out other ball of pie dough and place on top of the pie. Crimp the edges together by holding a pinched thumb and pointer finger on the outside edge and pushing a finger from the opposite hand into the dough between the thumb and pointer finger, pressing the dough together.
Bake at 350 F for 30 minutes, or until top is golden brown.