Place the chicken in a very large bowl, set aside.
Heat the olive oil in a skillet over medium heat.
Add the mushrooms and saute over until the liquid from the mushrooms evaporates and the mushrooms become golden brown, about 12 minutes.
Add the onion, garlic, and thyme, and saute until the onion is translucent, about 8 minutes.
Transfer the mushroom mixture to the bowl with the chicken.
In a separate bowl, whisk together the cream of chicken soup, milk, sour cream, 1/2 the butter, garlic powder and nutmeg.
Add the noodles, sauce, peas, 1 cup mozzarella and parsley to the chicken mixture. Toss until the sauce coats the pasta and the mixture is well blended.
Transfer the pasta mixture to a baking dish coated with cooking spray.
Stir the remaining cheese, breadcrumbs and butter together in a small bowl.
Sprinkle the cheese mixture over the pasta.
Bake, uncovered, until golden brown on top and the sauce bubbles, about 25 minutes.