Season the pork loin all over with salt and pepper.
Turn the Instant Pot to 'Sauté' mode and heat the olive oil.
Once hot, add the pork loin and sear on all sides until golden brown, approximately 3 minutes per side.
Remove the pork loin and set aside. Add the minced garlic to the pot and sauté for 1 minute until fragrant.
Pour in the chicken broth to deglaze the pot, scraping up any browned bits from the bottom.
Place the pork loin back into the pot, secure the lid, and set the valve to 'Sealing'.
Select 'Manual' or 'Pressure Cook' and set the time to 25 minutes on high pressure.
Once the cooking cycle is complete, allow for a natural release for 10 minutes, then quick release any remaining pressure.
Carefully remove the pork loin and let it rest while making the sauce.
Select 'Sauté' mode again, and stir in the heavy cream, Dijon mustard, and fresh thyme into the liquid in the pot.
Simmer the sauce until it thickens to your desired consistency, usually about 5-7 minutes.
Stir in the grated Parmesan cheese until melted and well incorporated.
Slice the pork loin and serve with the creamy Dijon sauce drizzled on top.