Add carrots, celery, onions, garlic, potatoes, and chicken in INSTANT POT.
Next add black pepper powder, salt, and Italian seasoning followed by chicken broth.
Close the lid and pressure valve. Select the PRESSURE COOK button on HIGH PRESSURE and cook for 8 minutes.
Once the pressure-cooking cycle is over, allow the pressure to release naturally for 5 minutes, then quick release the pressure.
Carefully take the chicken out with the help of tongs. Shred the chicken breast with the help of a fork.
Meanwhile make the butter and flour paste. Melt butter in a pan, once melted add all-purpose flour, and mix to form a paste.
Set the instant pot on the SAUTE function.
Add frozen peas and then add the milk. Stir to combine.
Add the shredded chicken back to the INSTANT POT. Stir to combine.
Once the liquid starts to bubble add the butter-flour paste to thicken the sauce. Mix and let simmer until the sauce thickens.
CANCEL the SAUTE button.
Serve hot with biscuits or pie crust.