Bring a large pot of water to a rolling boil and add potato chunks and garlic cloves. Turn heat down to a low boil and cook for at least 20 minutes or until the potatoes are soft when pierced with a knife or fork. Drain vegetables into a sieve or colander to get rid of the water. Place the pot back on the burner under very low heat and add back the drained potatoes and garlic. Now it’s time to mash the vegetables until smooth. You can put the vegetables through a ricer, or simply smash them in the pot with a masher until no lumps remain. Add the milk or half and half very gradually, stirring until you get a smooth, creamy consistency to the mashed potatoes. Add butter, the salt and pepper and mix thoroughly. Serve piping hot.