Press the sauté button on the Instant Pot and adjust to High. Add the butter and melt. Add onion and sauté for 5 minutes, or until slightly translucent. Add celery, carrots, and potatoes. Stir to combine and turn off the Instant Pot.

Place chicken on top of the vegetables, then pour the water mixed with Better than Bouillon, salt, pepper, garlic powder, thyme, and parsley over the chicken. Lock the lid, turn the sealing knob to sealing, then press the Manual or Pressure Cook button and adjust the time to 2 minutes.

Preheat the oven to 425º.

Allow a 5 minute natural pressure release, then turn the knob from sealing to venting and remove the lid. Remove the chicken and shred or dice. Press the saute button on the Instant Pot and add the chicken back into the pot, along with the frozen peas.

While the mixture comes back up to a simmer, whisk together the heavy cream and flour, then pour into the Instant Pot and stir to combine until thickened. Taste the filling and add additional salt to taste. Remove from the heat and let stand while preparing the pie crust.

Roll out a store-bought or homemade pie crust in a standard 9 inch pie plate or casserole dish. Pour the pot pie filling into the pie crust, then add the top crust and seal. Cut a couple slits in the top crust to allow venting. Brush with an egg wash or heavy cream for an even more golden crust. Use a pie crust cover or foil to protect the edges of the pie crust, if desired.

Place the pot pie on a foil-lined cookie sheet and bake for 30-35 minutes, or until the crust is golden and the bottom of the pie does not have any wet spots.

Let stand, uncovered, at least 15-30 minutes before serving (it will stay hot up to 3 hours).