Grate the mild cheddar cheese and parmesan cheese, then set them aside (it is better to grate these cheeses fresh as pre-grated cheese is coated in either cornflour or cellulose which will make your Mac and Cheese thick and gloopy).
Pour the macaroni pasta into the instant pot container.
Pour the chicken broth and water into the instant pot container (do not stir as this will make your Mac and Cheese gloopy and thick due to the starches being released).
Spoon in the required salt.
Close the lid and set the instant pot to pressure cook on high for 4 minutes.
After 4 minutes, do a quick-release on the instant pot and immediately open the lid (or it will continue cooking).
Turn the instant pot on low, sauté mode for 1 minute and add the mild cheddar cheese, parmesan cheese, mozzarella cheese, cream cheese, heavy cream, butter, and black pepper.
Stir the Mac and Cheese until all ingredients are incorporated.
Serve immediately.
Plate, serve, and enjoy!