Melt 1/2 stick of butter. Add 2 cans of mushroom soup. Chop the chestnuts and pimento. When soup comes to a good boil add the chestnuts and pimentos and stir well.
Pour 1/2 of the soup mixture in a casserole dish and sprinkle cheese, then put all of the string beans in, now pour the rest of soup on top of beans and sprinkle more cheese. Put in oven until real hot. On top of this add 2 cans of French fried onions and brown. Watch it as it will burn soon.