Anne's Chicken a la King

Granny gave me this recipe when I was a teenager in an old Macon ladies' club cookbook. So old, in fact, that the recipe told me to bring things to "the boil." Ha!
It was quite delicious! Kind of a big production, but worth the effort.
It said to boil a whole chicken, but I roasted mine to save time.

1 4-5 lb. fryer
4 T. butter
4 T. flour
salt to taste
6 T. chopped green pepper
1 c. mushrooms, cut (I just used a can of sliced, drained first)
1 c. chicken broth
1 pimento, chopped (I just used a little can, drained)
2 c. chopped chicken
2 egg yolks
2 c. whole milk
Rice, pasta or biscuits to serve it with

Wash chicken and remove giblets. Cover well with water. Season with salt and pepper to taste. Turn heat to high and bring to boil, then turn heat to low or medium, and simmer until cooked. Cool and remove from bone. You will have a lot leftover, which is great!
Melt butter in a saucepan on low heat. Stir in flour until well-blended. Stir in milk, chicken broth and salt. Cook until thick. Pour into beaten egg yolks and mix thoroughly. Mix chicken, green pepper and pimento. Heat a large sauce pan on high heat. Melt 2 T. butter. Add mushrooms. Cook 10 min. Add chicken and white sauce. Bring to boil, then turn off heat. Cover and keep warm until ready to serve.