Preheat your oven to 200°C (400°F). Place the prepared head of garlic, cut-side up, on a piece of aluminum foil. Drizzle the exposed cloves with 1 tbsp (15ml) of olive oil.

Wrap the aluminum foil tightly around the garlic head to create a packet. Place the foil packet directly on the oven rack.

Roast the garlic for 40-50 minutes, or until the cloves are very soft, tender, and slightly caramelized. The aroma should be sweet and fragrant. Remove from oven and let cool slightly.

While the garlic roasts, place the peeled and chunked potatoes in a large pot. Cover them with cold water by at least 2.5cm (1 inch). Add a generous pinch of salt to the water.

Bring the water to a rolling boil over high heat. Once boiling, reduce the heat to medium-high and simmer for 15-20 minutes, or until the potatoes are fork-tender. Be careful not to overcook them, as they can become mushy.

Drain the potatoes thoroughly in a colander. Return the drained potatoes to the hot, empty pot. Let them sit for 1-2 minutes over the residual heat to allow excess moisture to evaporate. This step is crucial for fluffy mashed potatoes.

Once the roasted garlic has cooled enough to handle, gently squeeze the softened cloves out of their skins directly into the pot with the drained potatoes. Discard the papery skins.

Add the chopped fresh rosemary, warmed milk, softened butter, 2 tbsp (30ml) of olive oil, salt, and black pepper to the pot with the potatoes and garlic.

Using a potato masher or a sturdy fork, mash the ingredients together until smooth and creamy. For an extra smooth texture, you can use a ricer or a food mill, or carefully pulse with an immersion blender for just a few seconds, being careful not to over-mix.

Taste and adjust seasoning with more salt and pepper if needed. Serve hot as a delicious side dish.