Heat the butter/oil in a large skillet over medium-high heat. Season the chicken with garlic salt & pepper to taste & the Italian seasoning. Add the chicken to the skillet and cook until golden brown, a few minutes per side. Remove the chicken & set aside.
Add the onions and garlic to the skillet and cook, stirring occassionally, for 3 minutes. Pour in the broth while scraping the bottom of the skillet to loosen the bits. Cook for another few minutes so that the broth reduces some. Add the spaghetti sauce and red pepper flakes (if using). Simmer for about 10-12 minutes.
Turn off the heat and add the cooked pasta, mozzarella, ricotta, & Parmesan. Stir in the cooked chicken. Stir to combine. Add a few small dollops of ricotta, a sprinkling of Mozzarella & Parmesan, & some chopped fresh basil on top for presentation, if desired.