Set the instant pot to saute and add the bacon. Cook until bacon is slightly crispy, then remove from the pot and drain on a paper towel lined plate.
Drain all but 2 tablespoons of bacon fat from the pot.
Add the macaroni, water, 2 tablespoons of butter, onion powder, mustard, paprika and garlic powder to the pot. Stir to combine.
Place the lid on the pot, turn the valve to seal and set to high pressure for 4 minutes.
When the timer is complete and turn the dial to vent.
When the pin has dropped remove the lid and stir the noodles.
Add the remaining butter, half of the cream and 1/3 of the cheese. Stir until cheese is melted and then add remaining cheese. Continue stirring until all the cheese is melted and then stir in ¾ of the bacon, reserving some for garnish.
Add remaining cream a little at a time until the sauce reaches your desired consistency.
Serve topped with remaining bacon and sliced green onion or chopped parsley if desired.