Place potatoes in a large pot and pour in cold water to cover by 1 inch. Add salt and bring to a boil. Reduce heat and simmer until potatoes are very tender, but not saturated or crumbly, 20–25 minutes.
4 pounds Yukon Gold potatoes, 1 Tablespoon Kosher salt
Drain potatoes, reserving ½ cup cooking liquid if making potatoes ahead. Return potatoes to pot and set over low heat. Gently stir until dry, about 1-2 minutes or until moisture is gone.
In the meantime, heat milk, thyme sprigs, bay leaves, garlic, and butter in a small saucepan over medium heat until butter is melted. Remove from heat.
1½ cups Whole milk, 2 cloves garlic, 5 sprigs Fresh thyme, ¾ cup Unsalted butter, 2 Dried bay leaves
Pass hot potatoes through a ricer into a large bowl. Do this while they are hot; if allowed to cool, the potatoes will become gummy. If not using a ricer, transfer to an electric mixer with paddle attachment and blend until desired consistency is reached.
Remove herbs from warm milk mixture and discard. Gradually add milk mixture to potatoes, stirring vigorously with a wooden spoon or paddle attachment until combined and smooth.
Season with salt and pepper. Serve with pats of butter on top and chives if desired. Enjoy!