Cook turkey sausage until thoroughly cooked. Cut sausage into 3 cm pieces. Set aside. Prepare ziti according to package; drain and rinse. Place a small amount of spaghetti sauce in the bottom of your casserole dish. Add cooked ziti, sausage, onion and peppers. Pour remaining sauce into the casserole. Add mozzarella to the mixture and thoroughly blend all ingredients together. Top with more mozzarella. Bake at 190ºC or 30 to 45 minutes or until cheese is slightly melted and lightly browned. Serve with a nice green salad and bread.