Measure 32 ounces (1 quart) of water. Add ground mustard, Magic Flavor Dust, and salt to the water. Stir to dissolve.
Pour pasta into pressure cooker insert. Place pat of butter on pasta. Pour seasoned water over pasta. Stir and make sure all pasta is submerged under the water.
Check pressure cooker lid to make sure sealing ring is properly seated, and close lid. Make sure Steam Release Valve is set to [Sealing].
Set pressure cooking program to [Pressure Cook] or [Manual]. Make sure pressure level is set to [High] pressure, if your model has dual pressure options.
Set pressure cooking time to half the lowest recommended cooking time on your particular package of pasta. If the amount is a half number, round down. For example, if the time on package says to boil for 9-11 minutes, cut 9 in half, which equals 4½. Then round down to 4 minutes.
Pause to wait for your Instant Pot to beep and start cooking or press [Start], depending on your model of pressure cooker.
While pasta is cooking, shred the cheddar cheese and soften the cream cheese by cutting into 8 pieces and microwaving for 30 seconds.
When pressure cooking time is finished, immediately Quick Release the pressure. If starchy liquid starts spewing from the valve, simply close the valve and proceed to do an intermittent steam release, also known as a controlled steam release.
After the float valve drops, open the pot and immediately drop the cream cheese in. Stir quickly to melt and incorporate the cream cheese. Then sprinkle the cheddar cheese over pasta and keep stirring rapidly until cheese melts and is well-incorporated.
Finish with fresh-cracked black pepper and grated parmesan cheese. Enjoy!