Roughly chop the potatoes into 2-inch chunks (no need to peel).
Place the potatoes in a large pot and cover with 1 inch of cold water. Stir in ½ tablespoon kosher salt. Bring to a boil.
Once boiling, cook until fork tender, about 8 to 10 minutes (pierce a piece of potato with a fork to assess doneness). Drain and return the potatoes to the pot.
When the potatoes are done, melt the butter in the same pot. Add the minced garlic and sauté for 1 to 2 minutes, until fragrant but not browned. Remove the heat. Add the potatoes back to the pot and pour in the milk.
Mash the potatoes with a masher, adding more milk if desired to get to a thinner consistency. Season with the kosher salt and plenty of fresh ground pepper. Taste and adjust seasonings as desired.