Place the chicken broth, heavy cream, garlic, salt and pepper into the Instant Pot liner.
If using raw chicken chunks, place the chunks into the liquid. If using pre-cooked chicken, skip this step.
Place the broken noodles into the liquid. Make sure they are all covered with liquid, but do not stir.
Place the lid on the Instant Pot, set the knob to sealing and then cook on Manual HIGH for 6 minutes. Allow for 6 minute NPR before turning the knob to quick release.
If using pre-cooked chicken, this is the time to add it to the pot.
Slowly add in the parmesan cheese, stirring the entire time. The cheese will melt into the sauce and thicken it.
Lastly, add in the spinach leaves and stir for a minute or so until the spinach has cooked down and is coated with the sauce.