Preheat the oven to 425°F. Melt the butter over medium heat in a 10 inch cast iron skillet.
Add the carrots, onion, celery and poultry blend, cooking for about 5 minutes. Stir in the garlic and cook for another 30 seconds. Add the flour and cook for 1 minute.
Slowly add the chicken stock and milk, stirring, until the mixture begins to bubble and thickens slightly, about 4-5 minutes. Add the turkey, peas, lemon juice and salt. Taste for seasoning and adjust if needed.
Roll out one pastry sheet into a 12 inch square on a lightly floured surface. Place over the cast iron skillet and cut 3 slits on the top of the puff pastry.
Brush the egg wash over the puff pastry and bake for 25 minutes or until golden brown and the filling is bubbling.
Notes
Homemade turkey stock can be used for extra flavor.
If you want a vegetarian version, replace the turkey with mushrooms and use vegetable stock instead of chicken stock.
If your puff pastry tears or cracks, rub with a bit of water and gently squeeze back together.
Make sure to cut slits into the pastry to allow the steam to escape.
I like a dark pastry, but if it is getting too dark for your liking, cover with aluminum foil.