Season pork chops with garlic powder, paprika, salt, pepper, basil, and rosemary.
Turn on the Instant Pot and press the “Saute” button.
Add olive oil and butter to the instant pot.
When oil is hot and butter is melted, add the pork chops and brown on each side; about 2 to 3 minutes per side.
Remove pork chops and transfer to a plate; set aside.
To the insert of the instant pot add the onions and cook for 1 minute. Add more oil, if needed.
Add sliced mushrooms and cook for 3 minutes.
Stir in chicken broth.
Return pork chops to the instant pot.
Secure the lid in place. Select “Pressure Cook” and set on HIGH for 10 minutes.
When the cooking time ends, release pressure and then do a quick release.
Carefully remove the lid and transfer pork chops to a serving dish.
Select the "Saute" mode on the Instant pot.
In a small bowl whisk together the cornstarch and water until combined; add it to the sauce in the instant pot. Stir constantly until gravy has thickened.
Optionally, stir in some heavy cream for a creamier gravy sauce and continue to cook for 1 minute, or until heated through.
Taste for salt and pepper; adjust to taste.
Serve the pork chops with the creamy mushroom sauce.
Garnish with parsley and serve.