Vintage Recipe--Chicken Tetrazzini

3 to 4 pound chicken, cut up
2 stalks celery, with leaves
1 medium onion, sliced
1 1/2 tsp salt
Boiling water
1/4 cup fat or butter
2 Tbsp flour
1/2 pound mushrooms, sliced
1 egg yolk, slightly beaten
3 Tbsp cream
1 8oz package noodles
3 Tbsp grated Parmesan cheese
1 Tsp butter

Put chicken, celery, onion and 1 teaspoon of the salt in a kettle. Add water to cover. Simmer until tender (about 1 1/2 hours). Remove chicken; strain broth. Chill chicken and broth. Remove skin and bones from chicken; leave meat in fairly large pieces. Skim fat from broth. Measure 2 tablespoons of the fat or butter into saucepan; blend in flour and remaining salt. Add 1 cup of the broth. Cook over low heat, stirring, until thickened. Cook mushrooms in remaining 2 tablespoons fat until brown. Combine egg yolk and cream. Stir slowly into sauce. Add chicken and mushrooms; heat to serving temperature. Meanwhile cook noodles in remaining broth, adding water if necessary; drain. Arrange in shallow baking dish; pour chicken mixture over noodles. Sprinkle with cheese; dot with butter. Brown under the broiler. Makes 4 to 5 servings.