Fleur de sel or other coarse grain sea salt for servingoptional
Trim the potatoes of any eyes or damaged areas and wash well in cold water. Pierce each potato with a sharp knife.
Place the rosemary, broth, oil, butter, and salt in the Instant Pot insert.
Place the potatoes in the Instant Pot insert with the pierced side down. Arrange as many potatoes as will fit in one layer in the bottom of the Instant Pot insert (there should be a little room to spare, they'll need the extra room later when they're cracked). Shake the insert a little so the broth coats the potatoes a bit.
Pressure Cook at High Pressure for 15 minutes, then Quick Release.
Many of the potatoes will have broken or cracked open during the pressure cooking.
Open the lid, and without removing the potatoes or the liquid from the IP, turn the Instant Pot to "Sauté" function (press "Cancel" button, then "Sauté" button). Cook the potatoes and the liquid until the liquid evaporates, and the potatoes begin to brown, about 10 minutes. Check the bottoms of the potatoes for browning and crispiness using a pair of tongs.
Remove the potatoes from the Instant Pot, and let them rest for 5 minutes. Transfer them to a serving platter. Sprinkle with chopped chives or rosemary and fleur de sel. Enjoy!