Pour the broth in the Instant Pot
Break the spaghetti strands in half and spread them in two layers using a crisscross pattern.
Use a spoon or spatula and kind of press down to make sure all the noodles get some water on them.
They don't need to stay in the water, but just get all of them wet.
Add 2 tablespoon of butter. Do not stir from this point on.
Close the lid and turn the vent to sealing position.
Set the Instant Pot to manual high pressure for 5 minutes.
Once done, let the pot release naturally for 5 minutes, and then release the remaining pressure with the manual pressure release.
Open the pot and stir the spaghetti, use tongs to stir well, and pick apart any stuck pieces.
There will be a few stuck pieces. Stir in the rest of the butter 2 tbsp, cheese and give it a nice stir.
The sauce will start to thicken.
Add in the freshly cracked black pepper and give it a quick stir
Serve it hot garnish it with some more grated cheese