On the Instant Pot press the SAUTE setting. When the message HOT is displayed, add the oil and sear the pork chops in batches until browned. Season with salt, pepper, and garlic powder. Remove onto a plate.
Add the onion and mushrooms, and sauté for 2-3 minutes then add the garlic and cook for 30 seconds.
Deglaze with chicken stock (add it all in), using a wooden spoon scrape off any bits stuck to the bottom of the pot.
Put the pork chops back in the instant pot, and sprinkle the Italian seasoning.
Secure the lid and set the vent to SEALING. Select the PRESSURE COOK/MANUAL setting and set the cooking time for 15 minutes at high pressure. The Instant Pot will take around 6-7 minutes to come to pressure before the time to cook. When the time is up naturally release the steam for 10 minutes, then quickly release the rest of the steam.
Carefully remove the lid, and remove the pork chops onto a plate.
Press on the SAUTE setting, add the heavy cream, and corn starch slurry (whisk 2 tablespoons of cornstarch with 2 tablespoons of water). Cook for a couple of minutes until the gravy has thickened. Switch off the sauté setting.
Put the pork chops back in so they’re covered with sauce (spoon sauce over the gravy). Serve over mashed potatoes or rice.