Heat a large skillet over medium heat and melt butter. 

Add diced onion and let it cook down for about 4-5 minutes, until it starts to become translucent. 

Next, add in the rest of your veggies and continue to cook until they have softened, about 5-10 minutes

Then add the garlic and cook until fragrant, about 1 minute. 

Next, add in the fresh herbs and stir to combine. Sauté for an additional minute.

Sprinkle the flour over the mixture and cook for an additional 2 minutes. 

Add in the gravy and use a whisk to combine with the flour. Once combined add in the cream or milk and whisk. Then add in the cooked turkey. Bring to a boil and simmer for 5 minutes. 

Add the mixture to a pie pan. 

Next, prepare the pie crust. Roll out the pie crust on a lightly floured surface and then place it over the pot pie mixture. I don't bother to crimp the edges, I just let them fall over the edge. Trim any excess that hangs off too far. 

Using a sharp knife, cut small slits in the pie crust.

Then in a small bowl, whisk together one egg and one tablespoon of water. Using a pastry brush, lightly brush the egg wash on top of the pie crust. I like to place the pie pan on top of a sheet pan incase the mixture bubbles over. 

Add to a 400 degrees F preheated oven and bake for 35-45 minutes or until the pie crust is golden brown. If the edges start to brown too quickly, you can tent the edges with aluminum foil. 

Remove from the oven and let it cool slight. Then slice and enjoy!