Crawfish Au Gratin Casserole

1 large onion, chopped
3 stalks celery, chopped
1/2 lb. butter
4 Tbsp. flour
1 1/2 can Pet milk
2 egg yolks
1 lb. Crawfish
10 oz. cheese, grated
Salt and pepper


Saute onions and celery in butter until soft. Add flour and blend. Remove from heat, add egg yolks, Crawfish, salt and pepper and the cheese. Place in casserole with cheese on top and bake at 350 F until bubbly.