Peel the potatoes and cut them into large chunks. Place the potatoes in the water and boil until fork tender, about 15 minutes. Strain the potatoes and set them aside.
Place the pot the potatoes were cooked in back on the stove over medium heat and melt the butter down, then stir in the garlic and seasonings. Let cook for 1-2 minutes until the garlic is fragrant.
Add the potatoes back into the pot and mash them with a potato masher. Stir them to combine with the garlic butter and seasonings. Serve immediately.