In a small bowl, combine the evaporated milk, cornstarch, salt, pepper, onion powder, hot pepper sauce and mustard and set aside.
Place the water and macaroni in your pressure cooker. Lock the lid into place and cook on high for 5 minutes and then quick release the steam and carefully remove the lid after all the steam has released.
Stir the macaroni to break it up, and then add the evaporated milk mixture you set aside earlier, cheddar cheese, Parmesan cheese, butter, and cream cheese. The pressure cooker will still be hot so your cheese will already start to melt. If the pressure cooker is not hot enough just press the saute button and stir until the sauce thickens and the cheese has melted. This will only take a minute or two.
Serve warm and enjoy!