1. Add the noodles, water and 2 tablespoons of the butter to the instant pot.
2. Close the lid, turn the valve to seal and set the pressure to high for 4 mintues.
3. When the timer is complete, turn the valve to release the pressure. When the pin has dropped, carefully remove the lid.
4. With the pot on Keep Warm, give the noodles a quick stir and then add the milk, sour cream, remaining butter, ranch seasoning and half of the cheese to the pot. Stir until well combined and cheese is melted then stir in the remaining cheese.
5. Add the bacon and continue to stir until the sauce is smooth. Add more milk as needed until the sauce reaches your desired consistency.
6. Serve immediatly garnished with chopped green onion and additional crumbled bacon, if desired.