Preheat oven to 350 degrees F.
Grease a shallow casserole dish with butter or non-stick spray
Place cut up chicken on the bottom of the casserole dish
In a small bowl mix soup and sour cream together until creamy.
Pour soup mixture over the top of the chicken
Melt the stick of butter in the microwave
Put crackers in a zip lock bag and crush with a rolling pin.
Add crushed crackers and poppyseeds to the butter and mix.
Sprinkle cracker mixture over the top of the casserole.
Bake for about 30 minutes or until heated through.
Let set for about 5 minutes before serving.