Turn your Instant Pot on to saute mode and add vegetable oil. When the oil is heated and shimmering, add the pork chops and brown, about 2-3 minutes on each side. You may need to do this in batches to avoid overcrowding. Remove the pork chops and set them aside.
Add more oil if the Instant Pot has gone dry. Add mushrooms and onion and saute until the onions are slightly translucent, about 3-4 minutes.
Add garlic and cook for 1-2 minutes until a light golden brown.
Add thyme, sage, rosemary, brown sugar, salt, and black pepper. Stir to combine and cook until fragrant, about 1 minute.
Turn saute mode off. Pour in half of the broth and place the pork chops on top. Seal the Instant Pot and cook on high pressure for 10 minutes.
Allow the pot to naturally release pressure for another 10 minutes. Once the 10 minutes is up, open the vent to release any excess pressure.
Remove the pork chops and set them aside.
In a small bowl, whisk the remaining broth and cornstarch together.
Turn on saute mode. Add the broth/cornstarch slurry and heavy whipping cream. Cook for 2-4 minutes until thickened, stirring constantly.
Serve the gravy over the pork chops. Garnish with parsley and serve.