Season the chicken breasts with the salt, black pepper, Italian seasoning, and garlic powder. Set the Instant Pot to Saute mode and add the olive oil.
Sear the chicken for 3 minutes per side until golden brown. Remove and set aside.
Add the minced garlic to the pot and saute for 30 seconds. Pour in the chicken broth and scrape up any browned bits from the bottom. Return the chicken to the pot.
Lock the lid, set the valve to Sealing, and cook on High Pressure for 10 minutes. Perform a quick release by carefully turning the valve to Venting, keeping hands and face away from the steam. Remove the lid once the pin drops.
Remove the chicken and set aside. Switch the Instant Pot to Saute mode. Stir in the heavy cream, sun-dried tomatoes, and parmesan cheese. Let it simmer for 2-3 minutes, stirring frequently.
Stir in the cornstarch slurry and continue simmering for 1-2 minutes until the sauce thickens. Add the baby spinach and stir until wilted.
Return the chicken to the pot, spoon the creamy sauce over the top, and serve over pasta or with crusty bread.