Place ravioli on the counter to thaw completely, about 30 minutes.
Heat a heavy skillet or Dutch oven over medium heat. Add Italian sausage and cook until no longer pink, 5 to 10 minutes. Remove sausage from skillet and set aside.
Add up to 1/2 tablespoon olive oil to the same skillet if needed, and scrape up the brown bits. Add onions, garlic, and 1/2 tablespoon Italian seasoning. Stir and cook for 1 to 2 minutes.
Add fire roasted tomatoes and sun-dried tomatoes and stir. Cook 2 to 3 minutes.
Stir in chicken broth and heavy cream. Add parmesan cheese and stir well. Allow to simmer and thicken for 2 to 3 minutes. If the sauce is too thick, add a little more chicken broth.
Add Italian sausage and spinach; combine well. Add ravioli. Use a spoon to cover each ravioli with cream sauce. Turn heat to low, cover, and allow to simmer for 3 to 5 minutes.