Ultra-Crispy Roast Potatoes -- For creamier potatoes with a slightly less crisp crust, substitute Yukon Gold potatoes for russets. Duck fat, turkey fat, or chicken fat will give the best results, but bacon fat or olive oil will work well.
Preheat oven to 425 degrees. Toss potatoes, oil, and rosemary on a rimmed baking sheet. Spread out potatoes in a single layer; season with salt and pepper. Roast, stirring once halfway through cooking, until potatoes are golden brown and crisp outside and