Peel the potatoes and cut into quarters, or about 1 ½-inch pieces. Place them in a large saucepan and cover with cold water. Add 1 teaspoon of salt and the whole, peeled garlic cloves, and bring to a simmer. Cook the potatoes until they are soft when pierced with a sharp knife. When they are cooked through, scoop out a cup of the cooking water. Drain the potatoes, then return them and the garlic to the pot.

Add the olive oil, a half cup of the water, and ½ teaspoon of salt to the pot along with the white pepper. Mash the potatoes until no lumps remain, then taste for seasoning. Add more salt and pepper if needed, and if they are too thick, add a bit more cooking water.

Oil a medium casserole dish, then transfer the potatoes to the dish. Sprinkle the parmesan cheese on top of the potatoes, and drizzle with another tablespoon of oil. At this point, you can refrigerate the potatoes for up to 8 hours.

Heat your oven to 375 F. Place the potatoes in the oven, uncovered, and bake just until they are warmed through. It should just take about 10 minutes. At the very end, turn the broiler on just to brown the cheese slightly on top. Serve warm, sprinkled with fresh chopped chives.