Wash, peel (if desired), and quarter the potatoes.
Place the quartered potatoes into the instant pot with 2 cups of water. (Add in the bullion if using and give it a quick mix)
Close the lid and set the valve to seal. Set the instant pot to (custom - high - 10 mins), and then select start.
Once the potatoes have finished cooking use the quick release. Open the lid once all pressure has been vented out and its safe to open.
Remove some of the liquid and set aside If needed. Add the butter and let it melt while you mash the potatoes.
Once the potatoes are mashed and the butter is melted, season to taste* with the garlic salt.
Once potatoes are done, place onto a plate and smother it with your favorite gravy... or other toppings of choice. Enjoy!
Notes
*When I season my potatoes I DON'T MEASURE. I just add a little bit here and there until it tastes the way I want it to. I would recommend adding an 1/8 - 1/4 tsp of seasoning at a time... always tasting and adjusting until it comes out (how you like it).