Use the back of a chef’s knife or a small masher to mash the roasted garlic into a paste before incorporating into the mashed potatoes. Set aside.

Place the potatoes and 1 teaspoon of the salt in a large pot and fill with enough water to cover the potatoes by 1 inch. Bring to a boil and cook until fork tender, about 20 minutes. Drain, reserving 1 cup of the cooking liquid.

Use a ricer or a potato masher to mash the potatoes in a large bowl. Use a rubber spatula to fold in the roasted garlic, olive oil, ½ cup of the reserved cooking liquid, the remaining 1 teaspoon salt, and several grinds of pepper. Continue folding until creamy, adding up to ½ cup more cooking liquid if desired for creamier potatoes. Serve hot with butter, chives, and/or rosemary, if desired.