Add in chicken, onion, carrot, celery, corn, garlic powder, onion powder, poultry seasoning, thyme, salt and pepper. Close and lock the lid.
Turn the valve to SEALING. Select MANUAL (or Pressure Cook). Set the time for 18 minutes.
When cooking ends, let the pressure release naturally for 10 minutes. Then carefully turn the valve to VENTING to release the rest of the pressure. Remove the lid.
In a small bowl, mix half-and-half and cornstarch together. Add mixture to pot along with peas, and stir.
Select SAUTE function and continue to cook soup, stirring constantly. Let the soup cook until it's thickened and bubbly (about 2 to 3 minutes).
Notes
You can use canned corn instead of frozen corn. Just drain and rinse corn kernels before adding them to the Instant Pot.