Preheat oven to 400F. Cut off the top 1/2-inch of the garlic off. Lay garlic on piece of tin foil, drizzle olive oil over garlic cloves and close tin foil. Roast for 30 minutes or until the garlic has softened completely and is very tender. Let cool and squeeze out the roasted garlic cloves. Coarsely chop.
In the meantime, place the potatoes in a large pot and cover with water by 1 inch. Cover and bring to boil and cook for 20-25 minutes over medium heat, until you can easily pierce the potato with a fork with very little resistance. Drain potatoes.
For Hearty, Skin-On Mashed Potatoes: Return the potatoes to the pot over low heat, add 3 tablespoons butter, 1/4 cup milk, salt and roasted garlic. Use garlic masher to mash. Do not over mix or the mashed potatoes will turn gummy. Taste and season with additional salt or milk if needed. Stir in chives.
For Creamy and Smooth Roasted Garlic Mashed Potatoes: In the pot, add 4 tablespoons of butter, 1/2 cup of heavy cream, salt and roasted garlic and turn the heat to low. Use a potato ricer to mash the potatoes into the pot. [TIP: If you find that the potatoes need a little more cooking, just put them in the microwave for an additional 2 minutes]. Stir the potatoes. Do not over mix or the mashed potatoes will turn gummy. Taste and season with additional salt or milk if needed. Stir in chives.