Add pasta, water, butter, salt, paprika, garlic powder, and cayenne to Instant Pot; mix.
Secure lid and set pressure release valve to sealing. Select Pressure Cook (or Manual) button, then set to High Pressure for 4 minutes.
When time is up, do a Quick Release, then open lid.
Stir in cream cheese until pasta is coated.
Add milk, cheddar, and Monterey Jack to pot. Stir until smooth, then season to taste with salt and pepper.
Serve Mac and Cheese immediately, sprinkled with green onions, if desired. Enjoy!
Notes
Stovetop Directions: Bring a large pot of salted water to a boil, then add pasta and cook until al dente. Drain Pasta, then return to pot. Stir in butter, cream cheese, paprika, garlic powder, and cayenne (skip salt for now). Then, mix in milk, cheddar, and Monterey Jack cheese until smooth. (Add more milk, if needed.) Season to taste with salt and pepper.