Set the Instant Pot to Saute Mode and add the butter, olive, oil and vegetables. Cook until the onions are soft and translucent, about 5 minutes.
Add 1 cup chicken broth and scrape up any bits that may have stuck to the bottom of the pot.
Season the cubed chicken with Italian seasoning, salt, and pepper. Add it to the pot.
Place the lid on the pot and ensure the pressure release valve is sealed. Hit Cancel, then hit Pressure Cook and set the timer for 8 minutes. When the time is up, flip the quick release valve.
Open the lid and switch to Saute mode.
Combine cream of chicken soup, and Ranch seasoning. Add HALF of the milk and HALF of the sour cream.
Let the soup simmer for about 5 minutes and serve!
Note: Only add the additional 1/2 cup of milk and sour cream if you prefer more broth.
Notes
Use whole milk, especially if cooking in the Slow Cooker, higher fat content will mitigate the possibility of having the dairy curdle.This stew is great served over homemade Buttermilk Biscuits!