Recipe(tried): Lobster Au Gratin

Hi JoAnn;
I've used this recipe several times and it is very good. It is in an old cookbook titled "Campbell's 100 best Recipes:
BROILED LOBSTER TAILS AU GRATIN
4 lobster tails (abvout 2 pounds)
1/2 cup sliced green onions
1/4 tsp. chervil, crushed (I don't use this)
2 Tbsp. butter or margarine
1 can cream of mushroom soup
1/4 cup sour cream
1/2 cup shredded cheddar cheese
Cook lobster tails in boiling water for 10 minutes or till done. Remove meat, keeping shells intact. Cut meat in 1" pieces. In saucepan, cook onion with chervil in butter until tender. Add soup, sour cream, and lobster. Heat, stirring occasionally. Spoon lobster mixture into shells. Top with cheese. Broil 4-5 " from heat until cheese melts. 4 servings