Preheat the oven to 350°F. Spray a 9x13 baking dish with non-stick spray and set aside. Bring a large pot of salted water to the boil. Cook the egg noodles for 6 minutes. Drain and rinse the noodles, and set aside. Mix the chicken, thawed mixed veggies, and onion together in a large bowl.
1½ pounds cooked chicken, 2 cups frozen mixed vegetables, ½ package egg noodles, 1 medium onion
Add the cream of chicken soup, sour cream, milk, salt, pepper, red pepper flakes, onion powder, garlic powder, and thyme to the bowl and stir to combine.
2 (10.5-ounce) cans cream of chicken soup, 1 cup sour cream, 1 cup milk, 1 teaspoon salt, ½ teaspoon black pepper, ¼ teaspoon red pepper flakes, 1 teaspoon onion powder, 1 teaspoon garlic powder, 1 teaspoon dried thyme
Stir the cooked egg noodles into the mixture.
Add 1 cup of the shredded cheddar cheese and mix well until combined.
2 cups freshly grated cheddar cheese
Pour the chicken mixture into the prepared baking dish.
Add the sleeve of Ritz crackers to the bowl of your food processor. Pulse 6 times until the crackers have broken up slightly. Drizzle in the melted butter. Then pulse another 6-8 times until the cracker resembles crumbs and the melted butter has been well incorporated.
1 sleeve Ritz crackers, ¼ cup salted butter
Sprinkle the crackers over the top of the chicken mixture and top with the remaining shredded cheese.
Place the dish in the preheated oven and bake at 350°F for 35 minutes, or until the top is golden brown and the sides are bubbly. Serve immediately.