Heat the oven to 400°F. Allow the refrigerated crust to sit according to its package directions so it is flexible enough to place in the pie plate without tearing.

In a medium bowl, combine the cooked chicken, reduced-fat cream of chicken soup, thawed and drained mixed vegetables, milk, poultry seasoning, garlic powder, and black pepper. Stir until the filling is evenly mixed and creamy.

For the lighter one-crust version, place the refrigerated pie crust over the top of the filling in a 9-inch pie plate after adding the mixture. If using two crusts, line the pie plate with one crust first, add the filling, then cover with the second crust.

Crimp the edges and cut several small vents in the top crust. Brush the surface with the optional egg wash made from one beaten egg and one tablespoon of water for a glossy golden finish.

Bake for 30 to 35 minutes, until the crust is golden brown and the filling is hot and bubbling. Since the chicken and sauce are already cooked, avoid baking much longer once the center is hot and the crust has browned.

Let the pot pie stand for 5 to 10 minutes before slicing. This brief rest allows the creamy filling to thicken so each serving holds together more neatly.