First chop your carrots, celery, green onion and sausage. Sausage should be in bite size pieces. On the bottom of your pressure cooker lightly drizzle olive oil. Saute sausage until golden brown. Set pressure cooker to manual and add in your chicken stock, diced tomatoes and seasonings. Turn pot on soup option. When complete let NR. You can then add in your pasta. I would recommend only half the box (1/2) pound. Turn your pot on manual mode, close lid and set to 4 minutes. Let NR. Put in bowl, top with cheese, and ENJOY.