On the Instant pot choose the SAUTE medium setting, and heat olive oil and melt the butter. Add onion, celery, carrots, and saute until the onion is soft and translucent. Add the chicken, cook for 1-2 minutes, then add garlic and cook for 30 seconds. Switch off the saute setting.
Add potatoes, chicken stock, herbs, salt and pepper to the pot.
Secure the lid and set the vent to SEALING. Select the PRESSURE COOK/MANUAL setting and set the cooking time for 4 minutes at high pressure. The Instant Pot will take around 10 minutes to come to pressure and start cooking.
When the cooking program ends, quickly release the steam. Remove the lid and discard the bay leaf, give everything a stir, and add in the peas or green beans, heavy cream, and cornstarch mixed with water. Stir, the cornstarch will thicken the stew
Serve with chopped fresh parsley as a garnish, freshly cracked pepper and crusty bread.