1. Preheat your oven to 400 F (200 C). Place the peeled garlic cloves on a small piece of aluminum foil. Drizzle with 1 tablespoon of olive oil, then fold the foil into a packet to seal. Roast in the preheated oven for 20-25 minutes, or until the garlic is very soft and lightly golden. The cloves should be easily mashable with a fork.

2. While the garlic roasts, peel and quarter the russet potatoes. Place them in a large pot and cover with cold water by about an inch. Add a generous pinch of salt to the water. Bring to a boil over high heat, then reduce heat to medium and simmer for 15-20 minutes, or until the potatoes are fork-tender and easily pierced.

3. Once cooked, thoroughly drain the potatoes in a colander. Return the drained potatoes to the empty hot pot. This step helps to evaporate any excess moisture, which is crucial for fluffy, non-watery mashed potatoes. Let them sit for a minute or two to steam dry.

4. Add the softened butter, warmed milk, remaining olive oil, roasted garlic cloves, salt, and pepper to the pot with the potatoes. Using a potato masher, begin to mash the ingredients together. Mash until the potatoes are smooth and creamy, with no large lumps remaining. Be careful not to over-mash, as this can lead to gummy potatoes.

5. Taste the mashed potatoes and adjust the salt and pepper as needed. If you prefer them even creamier, you can add a touch more warmed milk, one tablespoon at a time, until you reach your desired consistency.

6. Transfer the creamy garlic mashed potatoes to a serving bowl. Garnish with fresh chopped chives, if using, for a touch of color and fresh flavor. Serve hot and enjoy!