Preheat oven to 350 degrees F. Boil chicken breasts until cooked completely.
Mix the cream of chicken soup and the sour cream in a bowl. Remove chicken from water, allow to cool, and shred into thin pieces, or small chunks. Add the chicken to the sour cream, and soup mixture, stir well.
Place in a non greased baking dish. Sprinkle desired amount of poppy seeds on top of that. Crush the Ritz Crackers over the top, and softly press them down. Add the 1/2 stick of butter to the top after it has been melted in the microwave.
Place in the oven until it begins to bubble (about 12-15 minutes). Serve warm!