"Rotisserie chicken or leftover turkey promises this casserole will deliver in no time," says Rach, "but it is a great make-ahead too."
Bring a large pot to a boil for noodles.
In a large skillet over medium-high heat, melt half the butter. When it foams, add onion, carrot, celery and garlic and soften a few minutes, then add salt, pepper and thyme. Stir in flour to coat, add lemon zest, then whisk in stock and half-and-half and bring to a bubble and thicken sauce. Stir sour cream into sauce and combine, add cheese and melt, add chicken or turkey and half the poppy seeds, heat the meat through and adjust seasoning.
Cook pasta 5 minutes and drain, then combine with sauce and chicken or turkey. Place in a 9-by-13-inch casserole dish.
Melt remaining butter and stir in Worcestershire, hot sauce, granulated garlic, granulated onion and celery seed. Combine with Ritz crackers and parsley. Top casserole with crackers and Parm and pass under the broiler to brown in hot oven.