Cut onion into large chunks.
Salt and pepper the chicken, add rosemary or other herbs if desired.
Add some onion and garlic to the cavity.
Add broth or water to pressure cooker.
Place chicken on trivet breast side up.
Add the rest of your onion.
Secure the lid on your Instant Pot. Select Manual, high pressure, and set for 30-50 minutes depending on the size of your chicken. Mine was about 4 pounds so I did 45 minutes and it would have been okay with slightly less time.
Leave chicken in the pot and allow to naturally release the pressure.
Check the temperature and cook for 5 more minutes if not done.
Serve and enjoy! Don't forget to save the bones to make broth.
This is best for chickens that don't contain the neck and giblets. If bought fresh remove these pieces before freezing. Sometimes you can get them out while it's frozen but not always.