Helen's Garlic Mashed Potatoes

1 to 3 whole garlic heads
1 1/2 tablespoons olive oil
Black pepper to taste
4 pounds Idaho potatoes
6 tablespoons butter
2 teaspoons white pepper
2/3 cup hot milk or cream

First roast the garlic: Cut just the ends off the heads of the individual cloves but leave the papery skin on and the root end intact. Drizzle olive oil over the cut end and sprinkle with black pepper. Add 1/2 inch water to a small oven-proof pan and place garlic in it root end up. Bring water to a boil on top of stove and then place in a 350oF oven for 45 minutes. When the garlic head is cool enough to handle, just squeeze the plump cloves from their skins and push them through a sieve. Peel the potatoes and cook, covered in water, until a knife easily pierces the flesh. mash the potatoes, adding the butter, white pepper, and hot milk or cream along with the mashed cloves of roasted garlic. Combine well and serve hot.