Rinse turkey; drain and pat dry with paper towels. In a large saucepan, place the turkey,potato,carrots,onion,water and 1/4 teaspoon salt. Bring to a boil. Lower the heat and simmer,covered for 15 minutes or until the turkey is cooked through. Drain and cover and set aside.
Preheat the oven to 350F.In the same saucepan,whisk together the evaporated milk,flour,thyme,1/4 teaspoon salt,and pepper. Stir in 1/2 cup of chicken stock and cook over medium heat, whisking constantly, until the mixture starts to thicken. cook and whisk 2 minutes more or until thickened and bubbly. Stir in the turkey mixture.
Spoon the turkey mixture into a lightly greased 2-quart casserole. Place the pie crust on top of mixture in casserole and press slightly so crust is snug on rim of dish. You can trim crust or fold under extra crust and crimp edge. Cut slits in crust on top and brush with alittle milk. Bake for 20 to 25 minutes or until crust is golden brown. Let stand 5 minutes before serving.