Preheat your oven to 400°F (200°C) or prepare an air fryer.
Slice the top off 1 whole head of garlic to expose the cloves.
Drizzle the garlic head with 1 tablespoon olive oil, wrap in foil, and roast until golden and soft (about 30 minutes in an air fryer or 40 minutes in the oven).
Let the roasted garlic cool slightly, then squeeze the caramelized cloves into a small bowl and mash with a fork.
While garlic roasts, place 2½ pounds of whole, unpeeled, similarly sized potatoes into a large pot of cold, salted water.
Bring to a boil, then reduce heat and simmer for about 30 minutes, or until fork-tender.
Drain the potatoes well and let them sit for a few minutes so excess steam evaporates.
Slice each potato in half crosswise, press the cut side down through a potato ricer to separate the flesh from the skins.
Discard the skins and rice the potatoes directly into a Dutch oven or large pot.
Warm 4 tablespoons unsalted butter and 1 cup heavy cream together until the butter is fully melted.
Pour about ¾ of the hot butter-cream mixture into the riced potatoes.
Add the mashed roasted garlic, 1 teaspoon salt, ⅛ teaspoon black pepper, and ¾ cup grated Parmigiano.
Gently stir with a wooden spoon until just combined; avoid overmixing.
Taste and adjust seasoning with more salt and black pepper if needed.
Add more butter-cream mixture or parmesan to reach your desired consistency and flavor.
If the mash cools down, gently rewarm over low heat while stirring.
If the mash thickens too much, loosen it with a splash of warm cream or milk.
Serve warm and enjoy your comforting garlic mashed potatoes.
