Roasted mashed potatoes have elevated flavor over stove top cooking. Make this recipe for creamy baked mashed potatoes for a holiday side dish that everyone will love!
Preheat oven to 400°F. Place potatoes on a rimmed baking sheet or in a large baking dish and cover tightly with foil. Roast until very tender, 60-65 minutes. If using large red potatoes, reduce cook time to 50 minutes.
Using flat side of chef's knife, bruise or smash the garlic cloves. Using a vegetable peeler, remove a wide 3 inch strip of zest from lemon. Save lemon for other use.
Add garlic and lemon zest to a medium saucepan, then add milk, thyme, peppercorns, butter and kosher salt.
Bring mixture to a simmer over medium high heat, stirring occasionally so bottom doesn't scorch. When liquid comes to a simmer, remove from heat, cover pan, and let it sit for 30 minutes.
When potatoes are done roasting, use a small knife to remove skins, or leave skins on if you like (I like the roasted flavors they add). Mash them in a large pot with a potato masher. Alternatively, pass potatoes through a ricer or food mill fitted with the fine disk into the pot (see Note 2).
Pour infused milk through a mesh sieve into pot with potatoes; discard solids. Place potato mixture over medium heat and stir until milk is incorporated into potatoes. Taste and season with more salt if needed. Drizzle more melted butter on top before serving. Drizzle more melted butter on top before serving or cover and keep warm until ready to serve.
Notes
If using salted butter, start with half the amount of salt called for in this recipe. You can always add more if needed, but you can't remove it if you use too much.
I prefer to use a potato masher and keep the potatoes slightly chunky and rustic. If you prefer smooth and creamy mashed potatoes, then by all means rice the potatoes or use a food mill.