Preheat oven to 400 degrees F. Butter a 9” x 13” casserole dish or eight oven-proof ramekins. Set aside.

In a saucepan, add potatoes with just enough cold water to cover. Bring to a simmer and cook until just tender, about 8-10 minutes. Drain potatoes and set aside.

In a large, dry skillet, sauté the mushrooms until their water is released. Let mushrooms cook for 1-2 minutes longer until lightly browned. Remove from the skillet and add to the potatoes. Set aside.

In the same skillet, melt 2 tablespoons of butter. Add the diced carrots, onion, celery, and thyme leaves. Lightly season with salt and pepper. Sauté until just tender, about 10 minutes. Add to the potatoes and mushrooms. Set aside.

In the same skillet, melt the remaining 6 tablespoons of butter. Whisk in the flour, until smooth, to form a roux. Continue whisking for another minute – you want to cook out the raw flour taste, but you want the roux to remain light in color.

Slowly add the turkey or chicken broth, continuously whisking to avoid forming lumps. Add the whole milk and bring the mixture to a simmer, continuously whisking.*** Add the nutmeg and lightly season with salt and pepper.

Add the peas, diced turkey, and cooked vegetables to the sauce and allow everything to warm through. Taste and adjust seasoning as necessary.

Pour the mixture into the prepared casserole dish or ramekins. Roll out the refrigerated pie crust just large enough to cover the casserole. If you are making individual portions, do your best to square off the crust before cutting into eight pieces, large enough to cover the ramekins. Lay gently on top of the mixture and brush with the egg wash. Cut a few venting holes in the pastry.

Bake for 25 minutes or until the pastry is golden. Serve immediately.