Prep. Prep a 9X13" baking dish well for nonstick. Also, preheat your oven to 375.
Roux. Start by melting your butter in a medium saucepan over medium heat. Once the butter has melted you can whisk in your flour and continue to cook for another minute. Slowly add the broth and then the milk into the saucepan, whisking the ingredients until smooth. Then whisk in your seasonings and continue to cook until thickened (about five minutes), whisking occasionally.
Combine. Remove the saucepan from the oven and stir in your turkey and vegetables, mixing until well combined. Then transfer the mixture to your prepared baking dish, evenly spreading it out.
Crust. To make the crust, combine together your stuffing with your beaten egg in a mixing bowl. Then evenly spread the mixture over the ingredients in the baking dish, taking care to not press the topping through the mixture.
Bake. Bake your pot pie for 35-40 minutes or until the crust layer turns golden brown and the filling is bubbling.
Set. Let the pot pie sit for a few minutes before serving so that it can set.