Chicken Tetrazzini

4 cups cooked, diced chicken
1 - 8 ounce package of spaghetti noodles
2 cups sour cream
2 cans cream of chicken soup
1 - 8 ounce can of mushrooms
1 stick of butter
parmesan cheese for top of casserole

Mix all ingredients (except cheese). Pour into casserole dish. Top with cheese. Bake at 350 degrees about an hour.