Add onion to the pot and cook until softened, about 3 minutes. Add garlic and cook for 1 minute more until fragrant.
Stir in Italian seasoning, salt, and pepper.
Add the uncooked orzo and chicken broth to the pot. Scrape the bottom of the pot to remove any browned bits.
Nestle the partially cooked chicken back into the liquid. Do not stir after adding the orzo and liquid.
Secure the lid and set the vent to Sealing. Select Manual/Pressure Cook (High Pressure) for 5 minutes.
When the cooking time is complete, allow a Natural Pressure Release (NPR) for 5 minutes, then carefully switch the valve to Venting for a Quick Release (QR) of any remaining pressure.
Open the lid. Stir in the heavy cream, cream cheese cubes, and Parmesan cheese until smooth and creamy.
Let the mixture sit for 2-3 minutes to thicken slightly. Garnish with fresh parsley before serving.
Notes
For a thicker sauce, reduce the amount of chicken broth by 1/4 cup.
Shred the chicken after cooking if you prefer a shredded texture instead of diced pieces.
If you do not have heavy cream, you can substitute with whole milk, but the final dish will be less rich.