Thanksgiving dinner can feel like a game of Tetris, but this make-ahead mashed potato recipe gives you one less thing to juggle. It lets you prepare the potatoes up to two days in advance, then reheat them just before serving without sacrificing their rich flavor or velvety texture. The secret is in the technique: Simmer whole, skin-on Yukon Gold potatoes to keep them from absorbing excess water, then pass them through a potato ricer with plenty of butter.