Add the oil, butter, onion, celery, carrots, and garlic to a large soup pot. Sauté over medium-high heat for 5-7 minutes.
Stir in the flour and let it cook for about a minute.
Stir in the chicken broth, cream, and Italian seasoning, followed by the mushrooms, potatoes, and chicken.
Increase the heat to high and bring the stew to a gentle boil. Reduce the heat and simmer (lid off) for 25 minutes.
Take the chicken out and cut it up/shred it. Add it back in, then season the stew with salt & pepper to taste.
This isn't a super thick stew. It's got quite a soupy texture (especially day 1). For leftovers it definitely thickens up a bit.
I used 4 large chicken breasts weighing around 1.7 pounds (anything around 1.5 pounds is fine). Feel free to use chicken thighs. The meat is more likely to stay tender, especially after reheating.
Chicken is safe to eat when it's reached an internal temperature of 165F. Use an instant read thermometer to test for doneness.
Nutritional information is provided as a courtesy only and should be construed as an estimate rather than a guarantee. Ingredients can vary and Salt & Lavender makes no guarantees to the accuracy of this information.