Creating the perfect Turkey Potpie is simple and enjoyable if you follow these steps:

1. Preheat the Oven: Preheat your oven to 425°F (220°C).
2. Sauté Vegetables: In a large skillet over medium heat, melt the butter. Add the chopped onion, celery, and diced potatoes. Sauté for about 5 minutes until softened.
3. Make the Sauce: Stir in the flour, and cook for another minute, stirring constantly. Gradually add the chicken broth and milk, whisking until the mixture is smooth and bubbly.
4. Add Turkey and Vegetables: Stir in the diced turkey, frozen peas and carrots, thyme, garlic powder, salt, and pepper. Cook for an additional 2-3 minutes until heated through.
5. Prepare the Crust: Roll out one pie crust and fit it into a 9-inch pie dish. Pour the turkey filling into the crust.
6. Top with Crust: Roll out the second pie crust and place it over the filling. Seal and flute the edges. Cut slits in the top crust to allow steam to escape.
7. Egg Wash: Beat the egg and brush it over the top crust for a golden finish.
8. Bake: Place the potpie in the preheated oven and bake for 45-50 minutes, or until the crust is golden brown and the filling is bubbling.
9. Cool Slightly: Remove from the oven and let it cool for about 10-15 minutes before serving.

These steps will guide you in creating a Turkey Potpie that is sure to impress. The aroma alone will have everyone eagerly awaiting their first bite!