Prep. Preheat oven to 400ยบ F. Prepare two pie crusts according to the recipe directions. Roll out one pie crust dough and line a 9-inch pie pan with it. Wrap the pie pan with plastic wrap and refrigerate it until ready to fill with the pot pie filling. Wrap the second pie crust in plastic wrap and store it in the refrigerator.
Cook the pot pie filling. Add 2 tablespoons of butter, the onions, potatoes, celery, and carrots to a Dutch oven set over medium heat. Cook until the onions are translucent and the potatoes are slightly tender about 8 minutes. Add 2 more tablespoons of butter and allow it to melt. Stir in the flour, salt, and pepper and cook until thick, about 2 more minutes. Pour in the chicken stock and cream and bring to a boil. Stir in the turkey.
Assemble the pot pie. Ladle the pot pie filling into the bottom crust. Roll out the second pie crust dough on a lightly floured surface and place it on top of the pot pie. Use a sharp paring knife and trim away any excess pie dough from the edges of the pie pan. Crimp the edges closed. Cut slits in the top of the pie dough to allow steam to escape during baking. In a small bowl, whisk together the egg and a tablespoon of water for an egg wash. Brush the top crust with the egg wash.
Bake. Bake until golden brown and the pot pie bubbles, about 35 to 40 minutes.
Serve. Remove from the oven and allow it to rest for about 3 to 5 minutes before serving.
Notes
Storage Tips:To store leftovers. Cool the baked pie and store it in an airtight container in the refrigerator for up to 3 days.To make ahead. Prepare as directed and store in the refrigerator for up to 48 hours before baking.To freeze. Store in a freezer-safe, airtight container for up to 3 months. Thaw in the refrigerator overnight before reheating to serve. Additional baking time may be needed when baking from the refrigerator. Cover the pie if it is becoming too brown while baking.