Roast the garlic. Preheat oven to 400°F.
Cut the tops off of 2 heads of garlic. Wrap in aluminum foil and roast for 40 minutes
Gently rinse the potatoes and place them in a large pot. Add enough water to submerge the potatoes completely.
Add salt generously to the water and bring it to a boil. Boil the potatoes with their skins on until they are easily pierced with a fork. This could take up to an hour.
Let the potatoes cool, then peel off the skin. The skin should easily peel off.
Pass the potato through a ricer, food mill, or sieve.
Squeeze the roasted garlic cloves into the pot with the potatoes. Add one cup of grated Parmigiano Reggiano, 1½ teaspoons salt, pepper, and butter
To a saucepan, add milk, rosemary, and thyme. Bring to a simmer and let simmer for 2 minutes. Remove from the heat, cover, and let steep for 15 minutes.
Remove the sprigs of rosemary & thyme, then pour the warm milk over the potatoes.
Use a potato masher to mash and mix the ingredients
Top with remaining grated parm and parsley