Heat the oil in a shallow lidded casserole dish over a high heat. Season the chicken and fry for 2-3 minutes until browned all over. Scoop out of the pan to a plate.
Thinly dice the celery, onion and carrots into small cubes.
Add the butter to the same pan and add the onion, carrots and celery. Season with salt and pepper and fry off for 5 minutes until soft.
Chop the mushrooms and add to the pan.Continue for a further 4-5 minutes.
Turn down the heat to low and add the flour and cook out for a minute before adding the thyme and gradually adding the stock, mixing well.Turn the heat back up to a steady simmer and allow the sauce to thicken.
Once the sauce has thickened chop the potatoes.Return the chicken to the pan and add the potatoes.Add enough water to just cover the chicken.Bring to the boil and cover with a lid, leaving it on a simmer for 20 minutes until potatoes are almost tender.
Serve sprinkled with chives.
Notes
This Chicken & Potato Casserole is the type of one pot dinner that can be plonked at the centre of the dinner table and will safely feed the whole family