Roasted Garlic Potatoes

1 giant clove of garlic
4 pounds Idaho potatoes peeled and quartered
1 sweet potato peeled and quartered
2 teaspoons salt plus more to taste
1 cup butter
1 cup milk
1 teaspoon black pepper plus more to taste

roast the garlic clove in its skin for 20 minutes in a 350-degree oven remove squeeze off the skin and mash the garlic It should equal 1 tablespoon set aside put the white potatoes and sweet potato in a large pot cover with water add the 2 teaspoons of salt and boil until the potatoes are tender about 30 minutes and drain in a colander place the hot potatoes in a large bowl add the garlic butter and milk and, using a hand mixer whip the potatoes until very smooth add the black pepper and adjust the seasoning with additional salt and pepper to taste serve