Add the potatoes to the Instant Pot® and sprinkle with the garlic powder. Season with salt and black pepper, to taste, and stir to combine.
Pour water or broth into the unit and cover. Lock the lid into place and flip the pressure valve to “Sealing.” Select the “Manual” setting on high and adjust the cooking time to 2 minutes.
When the cooking time is complete, allow pressure to release naturally for 5 minutes. Then do a quick release for any remaining pressure. Once the pin drops and no more steam is coming out, carefully remove the lid and set it aside.
Turn the unit off and drain the potatoes completely. Return the potatoes to the unit and add melted butter and parsley. Season with additional salt and black pepper, if desired, and toss to combine.
To serve, transfer the potatoes to a serving bowl and top with some freshly grated Parmesan cheese, if desired. Enjoy!