Preheat oven to 400F.
Peel the papery skin away from the heads of garlic. Place on a cutting board and cut off the top 1-inch. Discard the top. Place one garlic head onto a small sheet of foil. Drizzle with EVOO and lightly sprinkle with salt. Wrap tightly and place on a small sheet tray in case it leaks. Do the same thing with the other head. Roast for 55-65 minutes or until golden brown and soft. Remove and let cool slightly.
While the garlic is cooling, peel the potatoes and cut the larger ones into quarters and the smaller ones in half so they are all roughly the same size, about 2 to 3-inch cubes. Place in a large stock pot and fill with cold water, making sure it covers the potatoes by at least 2-inches. Liberally season with salt.
Bring up to a simmer on medium high heat and cook for 20-25 minutes or until easily pierced with a knife. Before draining reserve 1 1/2 cups of the cooking liquid.
While the potatoes cook in a small sauce pot combine the half and half, butter, rosemary and the garlic cloves squeezed from the roasted head. Bring up to heat over low and barely simmer, not boil for 20 minutes.
After you drain the potatoes place them back into the stock pot. Using a hand masher, mash the potatoes until broken down into small pieces. Remove the rosemary sprigs from the pot and pour into the potato mixture. Switch to a hand mixer and carefully whip the potatoes until light, fluffy and smooth. Start adding 1/2 cup of the reserved cooking liquid until desired consistency. Taste for seasoning, adding more salt if needed and freshly cracked black pepper.
Spoon into a large shallow dish and drizzle with melted butter, rosemary sprigs and flaked sea salt. Serve.
Recipe Courtesy of Megan Mitchell