Cooking the polenta in chicken stock infuses it with robust savoriness, and melting the parmesan cheese into the polenta further adds a salty, nutty quality. It's the perfect balance to the acidic, tomato-forward sauce. And while this slow-cooker chicken dish is fancy enough to serve to guests at a dinner party, the use of presliced mushrooms and quick-cooking polenta keeps the hands-on time to a minimum. Garnish with fresh oregano and basil leaves, if desired.