Preheat the oven to 375 degrees F.
Place the garlic on a pie pan and drizzle with the oil. Season lightly with salt and pepper, and roast for until the garlic is very tender and golden brown, about 1 hour. Remove from the oven and let cool. When cool enough to handle, squeeze the head to release the cloves into a small bowl. Use a fork to mash the garlic until smooth.
Place the potatoes and 1 teaspoon of salt in a medium pot and cover with water by 1-inch. Bring to a boil. Reduce the heat to a simmer and cook until fork tender, about 15 minutes. Drain in a colander. Return to the saucepan over medium heat and cook 1 minute. Reduce the heat to low, add the mashed garlic and butter, and mash using a hand-held masher. Add the cream and continue to mash until thoroughly combined and the desired consistency is reached. Season, to taste, with salt and pepper, and serve immediately.
Yield: 6 servings