Preheat your oven to 400°F. While it's warming up, place your whole potatoes on a baking sheet and cover them with aluminum foil to lock in the moisture.

Slide the baking sheet into the oven and roast the potatoes until they're fork-tender, which should take about an hour.

Flavor Foundations: While the potatoes are roasting, take a saucepan and combine the peeled garlic cloves, milk, thyme, and peppercorns. Cut the butter into chunks and add it to the pan along with the salt.

Heat the mixture over medium until it gently simmers. Then, turn off the heat, cover the pan, and let it sit.

Once the potatoes are roasted, let them cool just enough to handle and then peel off the skins.

Transfer the potatoes to a large bowl or pot and mash them to your desired consistency. If you have a potato ricer or food mill, now's the time to put it to good use for an even smoother mash.

Strain the infused milk into the mashed potatoes, discarding the solids. Stir the mixture over low heat until it's beautifully creamy and smooth. Season to taste.

Spoon the mashed potatoes into a serving dish. Melt a bit more butter and drizzle it over the top.