About 1/2 tablespoon salt for potato cooking water
2 pounds red or Yukon gold potatoes, scrubbed well and large potatoes cut into smaller pieces
4 tablespoons olive oil
1/2 teaspoon salt, or to taste
Instructions
Preheat oven to 425°F.
Slice off the top of the garlic to expose the tips of the cloves. Place head on a square of foil large enough to wrap it. Drizzle the head with olive oil and wrap loosely in the foil. Place on a baking sheet and bake until tender and fragrant, about 35 minutes. Remove from the oven and let cool. Remove the garlic from the peels, pressing to express the paste, and mash with a fork or the back of a wooden spoon.
Place potatoes in a large stockpot and cover with cold, salted water. Bring to a boil. Cook until fork-tender, about 20 to 25 minutes.
When potatoes are tender, remove pot from heat and carefully pour 2 to 3 cups of the water into a heat-safe container such as a Pyrex pitcher or a saucepan. Drain off the rest of the water. Add the 4 tablespoons oil, mashed roasted garlic, 1/2 teaspoon salt, and about 1/3 cup of the potato cooking water. Mash to desired texture, adding additional water a little at a time until desired consistency is reached.