Preheat your oven to 400°F (200°C). Slice the very top off the head of garlic to expose the cloves. Place it on a small piece of aluminum foil, drizzle with olive oil, and wrap it up. Roast for 20-25 minutes until the cloves are soft and fragrant. Let it cool slightly, then squeeze the roasted cloves out of their skins into a small bowl and mash with a fork. Set aside.

Place the peeled and chunked potatoes in a large pot. Cover with cold water by at least 1 inch and add 1 tablespoon of kosher salt. Bring the water to a rolling boil over high heat, then reduce the heat to maintain a steady simmer. Cook for 15-20 minutes, or until the potatoes are very tender and a fork slides in with no resistance.

While the potatoes are boiling, combine the whole milk, heavy cream, and cubed butter in a small saucepan. Warm over low heat until the butter is completely melted and the mixture is hot to the touch. Do not let it boil. Keep it warm.

Drain the cooked potatoes thoroughly in a colander. Return the empty pot to the warm burner for 30-60 seconds to evaporate any remaining moisture. Place the potatoes back into the dry, hot pot.

Mash the potatoes using a potato masher for a classic texture or pass them through a potato ricer for the smoothest result. Avoid using electric mixers, which can make them gummy.

Pour about half of the warm milk mixture into the potatoes. Add the mashed roasted garlic, 1 teaspoon of kosher salt, and 1/2 teaspoon of black pepper. Gently fold and stir until incorporated. Gradually add the remaining milk mixture until you reach your desired creamy consistency. Be careful not to overmix.

Gently stir in the room temperature sour cream (or cream cheese), chopped chives, and parsley until just combined. Taste and adjust the seasoning with more salt and pepper as needed.

Transfer the mashed potatoes to a warm serving bowl. Create a well in the center and add an extra pat of butter (optional). Garnish with more fresh chives and a crack of black pepper. Serve immediately.