Ina Garten’s make-ahead mashed potatoes are a creamy, oven-baked side dish made by boiling and mashing Yukon Gold potatoes, then mixing them with butter, sour cream, cream, garlic, and Parmesan. The mixture is transferred to a baking dish and can be refrigerated for up to two days, making it easy to reheat and serve when needed.
3 pounds Yukon Gold potatoes, peeled and cut into large chunks
1 tablespoon kosher salt (for boiling water)
1 cup sour cream
½ cup whole milk or heavy cream, warmed
6 tablespoons unsalted butter, divided
2 cloves garlic, minced (optional)
½ cup freshly grated Parmesan cheese
Salt and freshly ground black pepper, to taste
Extra Parmesan and butter for topping
Place potatoes in a large pot, cover with cold water, and add 1 tablespoon salt. Bring to a boil, then simmer for 20–25 minutes or until the potatoes are fork-tender.
Drain the potatoes well and return them to the hot pot. Allow them to sit for 2–3 minutes to evaporate excess moisture. Then mash using a ricer or potato masher until smooth.
Stir in the sour cream, warm milk or cream, 4 tablespoons of butter, garlic (if using), and Parmesan cheese. Mix until well combined and creamy. Season with salt and pepper to taste.
Spread the mashed potatoes into a buttered 9×13-inch baking dish. Dot with remaining 2 tablespoons of butter and sprinkle with extra Parmesan.
If making ahead, let the dish cool completely, cover tightly with foil or plastic wrap, and refrigerate for up to 2 days.
Preheat oven to 375°F (190°C). Bake the mashed potatoes, covered, for 30 minutes. Uncover and bake for another 10–15 minutes, until lightly golden and heated through.