My Mom has been making this for years and I love hers, but I recently had a different version at a casual wedding I attended and thought it was delicious so I tried to recreate that version. This is what I came up with. Hope you enjoy it, my daughter loved it. The best part is I had all the ingredients on hand.
Simmer chicken breasts on stovetop in enough water to cover until cooked through. I season the water with salt and pepper. When cooked through, remove chicken and allow to cool. Shred chicken and reserve cooking liquid and set both aside.
In same pot on low heat, combine soup, seasonings and cooking liquid from chicken and stir. Simmer 10 minutes stir occasionally. Add cheese and stir to melt then add chicken.
Add cooked spaghetti and stir gently and cook additional 5 or so minutes until heated through. At this stage, you can always add more cheese on top if you want before serving. I don't think it is possible to have too much cheese.