Place fryer in Dutch oven, and cover with water, 1 t. salt and 1 t. pepper. Bring to boil, simmer 1 hour or until tender. Remove chicken from broth, saving broth. Debone chicken when cool and coarsely shred the chicken, set aside.
To reserved broth, add enough water to make 3 quarts of liquid. Bring to boil and cook spaghetti, drain and set aside.
In Dutch oven, heat olive oil, sauté bell pepper, onions and mushrooms. Add flour and next 4 ingredients. Stir until smooth. Cook 1 minute, stirring constantly.
Gradually stir in milk and cook until thick, stirring gently.
Add ¾ c. cheddar, stir until melts.
Add shredded chicken, soup, ½ c. parmesan, sherry and pimiento. Stir well.
Combine chicken mixture with spaghetti, tossing gently.
Spread mixture into greased 13x9x2” baking dish. Bake uncovered 350 for 20-25 minutes or thoroughly heated.
Combine remaining ¼ c. parmesan and paprika, mix well.
Sprinkle remaining 1 ¼ c. cheddar in diagonal rows across top of casserole. Repeat with sliced almonds and parmesan/paprika mixture. Bake another 5 minutes or until cheese melts.
Recipe by Geaux Ask Alice! at https://geauxaskalice.com/creamy-chicken-tetrazzini/