Pre-heat oven to 350°F.
Heat a large skillet over medium heat and add olive oil.
Sautéed carrots onion and celery until tender and add peas.
While veggies cook, in a large bowl, mix chicken, cream of chicken soup, sour cream and milk. Season with salt and pepper. Gently, fold in the noodles.
Once veggies are tender, add them to the noodle mixture and gently stir. Spread chicken casserole in a greased 9x13 baking dish. Cover with foil and bake for 30 minutes.
While the casserole bakes, prepare the cracker topping. Place crackers, into a sealable bag. Seal and crush the crackers. Add melted butter and parsley, seal, and mix with hands. Set aside.
After 30 minutes, remove foil and add crushed buttered crackers. Bake uncovered for an additional 15 minutes. Remove from oven and allow and allow casserole to rest for about 5 minutes before serving.