Cut the chicken breasts into bite sized pieces and sprinkle with 1 teaspoon of fine grind sea salt and 1 teaspoon of pepper. Set aside.
Finely dice (about ¼-½") 1 celery stalk, 1 carrot, and ½ of an onion.
Slice the mushrooms, cut the remaining 1½ onions into 2" chunks, slice the carrots into ¾" pieces, cut the celery into 1" pieces, and cut the peppers into 1-2" chunks.
Add the butter to the inner pot and turn on sear/sauté on high. When the butter has melted, add in the chicken and spread into 1 layer on the bottom of the pot. Add in the finely diced vegetables, but don't stir. Allow the chicken to cook for about 2-3 minutes to brown and then stir in the finely diced vegetables. Add the flour and stir to combine. Cook another 2 minutes, stirring frequently.
Deglaze the pot with the chicken stock and scrape the bottom of the pot to remove anything that may be stuck on the bottom. Add the remaining seasonings and bay leaves and stir.
Add the larger cut vegetables to the pot and stir. Cut the Yukon gold potatoes into about 1-1½" chunks and add to the stew. Grate the russet potato and add to the pot. You don't have to peel it, but you can if you want to.
Put the pressure lid on and turn the valve to vent. Select the slow cooker function on HIGH for 4 hours.
When the time is up, check the vegetables to make sure they are cooked to your liking. If you want them softer, use sear/sauté on medium and simmer until they are how you like them. Add in the cream, cut up inner leaves of celery and parsley if using. Stir.
See recipe notes½ for instructions on how to thicken the stew if it isn't as thick as you want.
Serve & Enjoy!