Set Instant Pot to saute function. Heat olive oil. Add celery, carrots, onion, and garlic to Instant Pot. Saute for 5 minutes. Add thyme, black pepper, sea salt and nutmeg. Stir to combine. Stir in soup and broth. Add mushrooms and green peas.
Close lid and pressure cook for 1 minute. Release steam. Stir in chicken and set Instant Pot to saute function. Simmer soup without lid for 2 to 3 minutes, or until chicken is warmed.
Serve soup with chopped parsley sprinkled on top and a biscuit on the side. Enjoy!