Bring a large pot of water to a boil. Add the chicken pieces to the boiling water and boil for a few minutes, and then turn the heat to medium-low and simmer, 30 to 45 minutes.
Remove the chicken and 2 cups of the chicken cooking broth from the pot. When the chicken is cool, remove the skin and pick out the meat (a mix of dark and white) to make 2 generous cups. Discard the bones and skin.
Cook the spaghetti in the chicken cooking broth until al dente. Do not overcook. When the spaghetti is cooked, combine with the chicken, 1 1/2 cups of the cheese, the green peppers, red peppers, seasoned salt, cayenne, soup and onions, and sprinkle with salt and pepper. Stir in 1 cup of the reserved chicken cooking broth, adding an additional cup if needed.
Place the mixture in a 9- by 13-inch casserole pan and top with the remaining 1 cup cheese. Bake immediately until bubbly, about 45 minutes. (If the cheese on top starts to get too dark, cover with foil.)
From Food Network Kitchens; after further testing and to ensure the best results this recipe has been altered from what was in the actual episode.