Add all ingredients (except lemon juice, spinach and Parmesan cheese) to pressure cooker.
Set to High Pressure. Cook for 15 minutes. Quick release.
Shred chicken & add back to the soup. Add lemon juice and spinach.
Top with Parmesan cheese before eating.
Note: if you don't have a pressure cooker, you can use a slow cooker instead. Cook for 3 - 4 hours on high or until chicken is at least 165 degrees.