Peel the potatoes and cut into 1 to 1 ½ inch pieces.
Put the potatoes into a large pot, add the bay leaf, 1 ½ tablespoons salt, and cover with cold water. Bring to a boil over high heat, then reduce heat to maintain a rolling boil and cook until the potatoes fall apart when poked by a fork, about 20 minutes.
Drain the potatoes into a colander. Let them sit 2 to 3 minutes to allow moisture to escape. Remove the bay leaf.
While the potatoes are cooking, heat the milk, butter, and garlic in a small saucepan over low heat. Allow the garlic to infuse the milk but do not boil!
Transfer the potatoes to a mixing bowl and give them a rough mash with a potato masher. Begin mixing the potatoes with an electric mixer and slowly pour in half the milk mixture (remove garlic cloves first for easier pouring).
Continue mixing until the potatoes are thick and creamy with very few lumps, and adding the warm milk as needed. Season with the remaining salt to taste.
Notes
Alternatively, you can put the potatoes through a ricer or food mill into a bowl. Add the hot milk and mix together with a spoon.
If you get the potatoes too wet return your stockpot and simmer on low, stirring constantly until the potatoes tighten back up.
The amount of milk and butter you need will vary based on the type of potato you use. I typically use ¾ of the mixture.