Put the potato in a large saucepan, cover with cold water and swirl the potatoes around with your hands until the water turns cloudy. Drain the potato and rinse under cold water. Return to the pan and cover with cold water, along with a generous amount of salt (roughly 2 tablespoons). Bring to the boil over high heat, then cook the potato for 15 minutes or until soft – a skewer or knife should be able to go through them with no resistance.
Drain the potato in a colander and cover with a tea towel. This will allow the potato to steam and remove as much moisture as possible. Leave to sit for 15 minutes. Mash the garlic confit cloves with a fork and set aside.
Over a large saucepan, pass the potato through a potato ricer or fine-mesh sieve. In two batches, stir the garlic confit and two-thirds of the butter through the potato with a spatula, until smooth and blended.
Slowly incorporate the milk until you have a slightly smooth consistency. The potatoes will have some texture to them.
Sprinkle with chives and a drizzle of extra garlic confit olive oil.