This is an easy, one pot(pressure cooker) meal. It could easily be converted to a crock-pot or stove-top dish. Cook everything in one pot, smash the potatoes, add cheese and you've got a delicious meal on the table with not a lot of fuss. I saw a similar recipe for a beef roast, but only had chicken, so I improvised...it turned out good!
Heat olive oil in bottom of pressure cooker over med.-high heat. Add chicken, salt and pepper to taste and lightly brown on all sides(work in batches if necessary to avoid overcrowding the pan.) Remove with a slotted spoon.
Add carrots, celery and onion to remaining oil and cook and stir for 3-4 min.
Put the potatoes on top of the veggies and pour the chicken broth over all. Salt and pepper the potatoes.
Put the lid on the pressure cooker and bring up to high pressure. Cook for 10 min., then quick-release pressure and remove lid. Place the chicken on top of the potatoes, dot with the 2T of butter and replace lid. Bring back up to pressure and cook 15 min. more. Release pressure and remove chicken to a serving bowl. Carefully remove the potatoes with a slotted spoon into another bowl(you may get a few pieces of the other veggies, too..that's ok.)
(At this point if you want to thicken your broth into a gravy, do that with flour or cornstarch or whatever you use, heating until desired thickness). Return chicken to broth and veggies and stir to combine.
Add the cheese to the potatoes and coarsely mash with a potato masher or hand held mixer. (you want some texture here, not whipped potatoes)
Ladle some stew into a bowl, top with a mound of the potatoes and sprinkle with parsley.