Pour the water into the Ninja Foodi. Add the macaroni noodles, butter, and salt, ensuring the noodles are submerged.
Close the lid and set it to pressure mode. Cook on HIGH pressure for 1 minute, then perform an instant release and carefully open the lid.
Mix in the whole milk, evaporated milk, 12 ounces of the shredded cheese, dried mustard, garlic powder, and black pepper.
Switch to the Air Fryer function, set the temperature to 320°F, and set the timer for 8 minutes. Press START/STOP to begin cooking.
Stir the mixture to combine, then sprinkle the remaining cheese on top. Continue cooking for an additional 8 to 10 minutes.
Once cooking is finished, let it sit for 10 minutes before serving.
