Large pot of creamy chicken noodle soup with shredded chicken, broth, cream of mushroom soup, broken spaghetti noodles, poultry seasoning, lemon pepper, and milk.
Melt the butter in a large pot over medium-low heat. Add the onion and cook 5 to 7 minutes, until soft and translucent. Add celery and carrots here if using.
Add the shredded chicken, chicken broth, cream of mushroom soup, broken spaghetti, poultry seasoning, and lemon pepper. Stir until the soup is fully incorporated into the broth.
Increase heat to medium-high and bring to a full boil, stirring occasionally so the noodles do not stick.
Reduce heat to medium-low and simmer for 45 minutes, stirring about every 10 minutes.
After 45 minutes, stir in the milk. Return to a low simmer for a few minutes without boiling hard.
Taste and adjust seasoning with salt if needed. Serve warm.
Notes
Add the milk at the end so it does not scorch or curdle during the long simmer. Stir every 10 minutes while the noodles cook so they do not stick to the bottom. Broken spaghetti gives a lighter soup texture than egg noodles. Use a heavy-bottomed pot if possible.