• Preheat oven to 325°F. Lightly grease a 9×13-inch baking dish with cooking spray.

  In a large mixing bowl, combine the cooked chicken, cream of chicken soup, milk, shredded cheese, uncooked macaroni, and onion (if using). Stir until evenly mixed.

  Pour mixture into the prepared baking dish and spread evenly.

  Cover tightly with aluminum foil and bake for 1 hour and 15 minutes, or until pasta is tender and casserole is heated through.

  Remove from oven and let rest for 5–10 minutes before serving. Optional: sprinkle additional shredded cheese on top before serving.

Notes

• This casserole may look loose before baking, but it thickens as it cooks and sets while resting.

  Use leftover rotisserie chicken for an easy shortcut.

  For extra flavor, add a pinch of garlic powder or black pepper to the mixture.

  Leftovers reheat well and can be stored in the refrigerator for up to 3 days.