Peel and cut Yukon gold potatoes into 1-inch pieces. Place them in a large pot and cover them with cold water enough to cover by 1-inch.
4 pounds Yukon Gold potatoes
Add salt and bring to a boil. Once boiling, reduce the heat and simmer until the potatoes are tender, but not over-saturated or crumbly, about 20-25 minutes.
1 Tablespoon kosher salt
Drain the potatoes. Return the potatoes to a pot and set them over low heat. Gently stir the potatoes until they're dry, about 1-2 minutes or until all moisture is gone.
In a small saucepan over medium heat, heat milk, thyme, bay leaves, garlic, and butter. Once the butter melts, remove from heat.
1½ cups whole milk, 2 cloves garlic, 5 sprigs thyme, 2 Dried bay leaves, 1½ sticks unsalted butter; equal to ¾ cup; plus more for serving
Pass the hot potatoes through a ricer into a large bowl. Do not let the potatoes cool first. They must be hot, or they will become gummy! If you don't have a ricer, or would prefer, you can use an electric mixer with a paddle attachment to mix the potatoes.
Remove the thyme sprigs and bay leaves from the warm milk mixture and discard.
Gradually mix the milk mixture into the potatoes, stirring with a wooden spoon or electric mixer with paddle attachment until combined and smooth.
Season with salt and pepper to taste. Serve topped with butter and chives, if desired.