Set the Instant Pot to the sauté setting and add the olive oil. Once hot, add the cubed chicken and season with salt, pepper, and Italian seasoning. Sauté until browned, about 5 minutes.
Add the minced garlic to the pot and sauté for an additional minute until fragrant.
Pour in the chicken broth and scrape any browned bits from the bottom of the pot to deglaze.
Break the fettuccine pasta in half and add it to the pot, ensuring it is submerged in the broth.
Close the lid of the Instant Pot, set the valve to sealing, and cook on high pressure for 6 minutes.
Once cooking is complete, do a quick release of the pressure. Carefully open the lid.
Stir in the heavy cream and grated Parmesan cheese until smooth. If the sauce is too thick, add a bit more chicken broth to reach desired consistency.
Taste and adjust seasoning as necessary with salt and pepper.
Serve immediately, garnished with chopped parsley.
Notes
For a thinner sauce, add more chicken broth as needed.