Poppy Seed Chicken Casserole

2-4 chicken breasts, cooked and cut up
1 tube Ritz crackers, crushed
1 can cream of mushroom soup, undiluted
1 can cream of chicken soup, undiluted
8 oz. sour cream
1 Tbs. poppy seeds

Topping:
1 tube Ritz crackers, crushed
3-4 Tbs. butter, melted

In large bowl, combine all ingredients except for topping. Pour into a casserole (I use a 11x7) dish. Combine topping ingredients and sprinkle on top of casserole. Bake at 325 for 30-35 minutes or until hot and bubbly.