In a large pot with boiling salted water cook rotini pasta until al dente. Drain.
Meanwhile, in a large Dutch oven cook sliced Italian sausage until brown. Add cubed chicken and cook until no pink remains in either meat. Add onion, garlic, green bell pepper, Italian seasoning, salt and ground black pepper and stir together. Cover and simmer until vegetables are tender. Stir in tomatoes, spaghetti sauce, mushrooms, and zucchini. Simmer until zucchini is tender yet crisp.
