Preheat the oven to 400°F. Wrap the whole bulb of garlic in aluminum foil and roast in the oven for 30 to 40 minutes or until the cloves feel soft.

Remove from the oven. When cool enough to handle, remove the skins from each clove of garlic and chop the cloves. Set aside.

While the garlic is roasting, bring a pot of water to a full boil.

Chop the potatoes into large chunks and place them in a steamer. Place the steamer with the potatoes into the pot of boiling water. Cook for 20 minutes or until potatoes are soft when poked with a fork.

Add all of the ingredients to a large pot and mash the potatoes using a potato masher (do this while the potatoes are still hot so that the cheese and butter melts).

Pour the mashed potatoes into a large serving dish and garnish with green onion.