Poppy Seed Chicken Casserole

5 boneless chicken breasts, cooked
1 can cream of chicken soup
8 ounces sour cream
4 cups Ritz crackers
1 stick butter, melted
1 tablespoon poppy seeds
Cut chicken breasts up into small chunks. Coat a casserole dish with non-stick cooking spray. In a bowl, mix chicken, cream of chicken soup and sour cream. Dump this mixture into the casserole dish and spread evenly.
    Crush crackers and mix with melted butter. Spoon cracker mixture over chicken. Sprinkle poppy seeds on top. Bake uncovered at 350 degrees for 30 minutes or until lightly browned.