Combine all ingredients except heavy cream and spinach in the slow cooker.
Cook on low for 2-3 hours (just check to see if the tortellini are done. An hour might even be sufficient, but I didn’t check it after an hour).
Stir in the heavy cream and spinach.
Let it cook for about another 10-15 minutes, or until the spinach has thawed and heated to the temperature of the soup.
Serve and top with parmesan cheese.