If using roasted garlic: preheat oven to 400F. Slice the top off a head of garlic, drizzle with a little olive oil, wrap in foil and roast for 30 to 35 minutes until soft and golden. Let cool, then squeeze cloves out of their skins. If using fresh garlic, mince finely and sauté in 1 tablespoon butter over medium heat for 1 to 2 minutes until fragrant.

Place the peeled and cut potatoes in a large pot and cover with cold water by about an inch. Add 1 teaspoon salt. Bring to a boil over medium-high heat, then reduce to a simmer and cook until potatoes are fork-tender, about 15 to 20 minutes.

Drain the potatoes well and return them to the warm pot. Let sit for a minute over low heat to dry out any excess moisture, shaking the pot occasionally so they do not stick.

Mash the potatoes using a potato masher, ricer, or food mill depending on your texture preference. For the creamiest, use a ricer or food mill; for a slightly rustic texture, a masher is fine.

Heat the milk or cream with the butter until the butter melts and the mixture is warm. Slowly add the warm dairy to the mashed potatoes, stirring gently. Add the roasted garlic (or sautéed fresh garlic) and sour cream, then season with additional salt and pepper to taste.

Adjust the texture by adding more warm milk or a little reserved potato cooking liquid if the mash is too thick. Fold in chopped chives or parsley if using.

Taste and correct seasoning. Serve hot in a warmed bowl with a pat of butter on top and a sprinkle of chives.