Roast the Garlic: Preheat oven to 400°F (200°C). Cut the top off the head of garlic, exposing the cloves. Drizzle with olive oil, wrap in aluminum foil, and roast for 45-60 minutes, or until the cloves are soft and fragrant.
Prepare the Potatoes: Peel and quarter the potatoes. Place them in a large pot and cover with cold water. Add salt to the water as this will help season the potatoes from the inside out.
Cook the Potatoes: Bring the potatoes to a boil and cook until they are fork-tender about 15-20 minutes. Don't overcook them, or they'll become waterlogged.
Drain the Potatoes: Drain the potatoes well in a colander. Return them to the pot.
Squeeze Out the Garlic: Once the roasted garlic is cool enough to handle, squeeze the roasted garlic cloves into the pot with the potatoes.
Mash the Potatoes: Use a potato masher or ricer to mash the potatoes and garlic together until smooth. Don't overwork the potatoes, or they'll become gluey.
Add Butter and Cream: Add the butter and cream to the mashed potatoes. Stir until well combined, using a wooden spoon or spatula.
Season: Season with salt and pepper to taste.
Adjust Consistency: If the mashed potatoes are too thick, add more cream or milk until you reach your desired consistency. Be careful not to add too much liquid, or you'll end up with runny potatoes.
Taste and Adjust: Give the mashed potatoes a final taste and adjust the seasoning as needed. Do your mashed potatoes need a little more salt?
Serve: Serve hot, garnished with fresh herbs, if desired.