In a cast iron skillet combine chicken, pre-cooked smoked sausage(roughly chopped), cheeses, onion, and spaghetti sauce. Stir to combine. Heat to a simmer on low heat, then heat through for about 10 minutes more.
In the meantime prepare spaghetti according to package directions. I always cook my spaghetti in salted water, and a little vegetable oil. Drain spaghetti and set aside.
Serve chicken-sausage mixture over hot spaghetti and enjoy. You can sprinkle with more parmesan cheese on top if you like.
***As a special note*** When I cook my sausage, I boil it in the skillet in water, until the internal temperature comes to at least 160 to 165 degrees.****