Preheat oven to 250F. Place the garlic and oil in a small pot with a lid and place in the oven for 30-40 minutes.
In a saucepot, combine potatoes with enough cold water to generously cover. Add salt to the water. Boil the potatoes until fork soft.
Drain potatoes and place back into pot. Mash potatoes with butter. Add sour cream, oil-poached garlic cloves and salt & pepper to taste. Garnish with parsley.