Fill a medium pot with water, add a generous pinch of salt, and bring to a boil over medium-high heat.
Add the potato pieces and boil for 7-8 minutes or until fork-tender.
While potatoes are cooking, combine butter and milk in a small saucepan. Heat over medium heat, whisking occasionally, until butter is completely melted. Alternatively, microwave in 30-second intervals, whisking between each, until butter melts.
Drain the cooked potatoes thoroughly and return them to the pot.
Mash the potatoes to your desired consistency using a potato masher or fork.
Gradually stir in the warm butter-milk mixture until fully incorporated.
Season with garlic powder, salt, and pepper. Stir well and adjust seasonings to taste. Set aside.