Break the spaghetti noodles in half and place them in the pot. Be sure to place them in a random pile (like a haystack) and not tightly packed or they will stick together.
Cut the chicken breast in half lengthwise (to make each chicken breast look like 2 thinner breasts), season with salt and pepper and place them on top of the noodles.
Pour the marinara sauce on top of the chicken and noodles.
Place the lid on the pot, turn the valve to seal, and set the pressure to high for 8 minutes.
Once the timer is complete, turn the valve to release pressure.
Open the lid and remove the chicken.
Place the cream cheese in the pot and close the lid.
With two forks, shred the chicken.
Open the lid and stir the cream cheese into the noodles.
Dump the chicken into the pot and stir to combine.
Serve with fresh parmesan cheese, or chopped herbs
While the cook time of this recipe is only 8 minutes, the total cook time is approximately 25 minutes when you allow time for the pot to come to and release pressure. This is an estimate based on my instant pot and may vary slightly between models.