Season the chicken breasts on both sides with salt, black pepper, and italian seasoning. 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 butter and garlic to the pot, cooking for 30 seconds until fragrant. Pour in the chicken broth and scrape up any browned bits from the bottom.
Add the chopped sun-dried tomatoes and return the chicken to the pot. Lock the lid and set the valve to sealing. Pressure cook on high for 8 minutes.
When the cook time is complete, do a quick pressure release by carefully switching the valve to venting. Remove the lid and transfer the chicken to a plate.
Set the Instant Pot to saute mode. Pour in the heavy cream and stir in the parmesan cheese. Let the sauce simmer for 3 to 4 minutes, stirring frequently, until it thickens and becomes creamy.
Add the fresh spinach to the sauce and stir until it wilts, about 1 to 2 minutes. Return the chicken to the pot and spoon the sauce over the top. Add red pepper flakes if using.
Garnish with fresh basil and serve with pasta, rice, or crusty bread.