Add pasta to the bottom of the Instant Pot. Pour in the chicken broth, heavy cream, fire-roasted tomatoes, salt, pepper, Italian seasoning, and minced garlic. Stir well to combine.
Add cream cheese cubes on top of the mixture. Do not stir after adding the cream cheese.
Place the chicken on top of the mixture and season lightly with salt and black pepper.
Close the lid and set the valve to the sealing position. Select the Pressure Cook button and set it to 8 minutes on high pressure.
Allow the pot to naturally release for 7 minutes, then carefully turn the valve to venting to quick release any remaining pressure.
Remove the chicken and stir in the fresh spinach. Let it sit on the Keep Warm setting until the spinach wilts.
Shred the chicken using kitchen shears or two forks, then return it to the pot and stir everything together.
Serve hot with grated parmesan cheese and fresh basil, if desired.
