Sweet Potato Purée with Streusel Topping

Preparation Position rack in center of oven and preheat to 400°F. Butter 9- by 13-inch baking dish or 2-quart casserole. Line rimmed baking sheet with aluminum foil. Pierce each potato with fork and transfer to baking sheet. Bake until tender, about 50 minutes. Cool until easy to handle. Meanwhile, make streusel: In medium bowl, combine flour, 3/4 cup brown sugar, and 1 stick butter. Rub mixture between fingertips until blended and crumbly. Set aside. Halve potatoes lengthwise and scoop out flesh into large bowl. Add remaining 1/3 cup brown sugar and 3/4 stick butter and mash with potato masher or, for a smoother purée, handheld electric mixer. Spread mixture in prepared dish and cool completely. (Streusel and purée can be made up to 2 days ahead and refrigerated, separately, covered.) Sprinkle streusel over potatoes. Bake until golden brown, about 40 minutes. Let stand 5 minutes before serving. (Completed dish can be prepared up to 1 day ahead and refrigerated, covered. Remove from refrigerator 1 hour before reheating and let come to room temperature. Bake, loosely covered with foil, until heated through, about 25 minutes.) Variation: Sweet potato purée with marshmallows: Omit streusel. Spread purée in baking dish, cover with foil, and bake until heated through, about 30 minutes. Sprinkle top with 3 cups miniature marshmallows and broil until marshmallows are lightly browned, about 1 minute. Serve immediately. Test-Kitchen Tips:•Most American cooks use the terms "sweet potato" and "yam" interchangeably, but there are actually three different types of vegetable referred to by these terms: The true sweet potato (also known as a boniato), available at Asian and Latino markets, has pale yellow flesh, skin with a purplish cast, and a chestnutlike flavor that isn't sweet at all. The true yam, also called a ñame (NYAH-meh), is a large tuber with scaly brown skin that's a staple of Caribbean, African, and Hispanic cuisines. The familiar, bright-orange-fleshed tubers called for in this recipe are a third type, a variety of the sweet potato that are often called "yams" to distinguish them from yellow-fleshed "true" sweet potatoes. The Louisiana, jewel, or garnet varieties will all work well. •While some recipes for sweet potato purée call for boiling the potatoes, roasting gives a much sweeter, more concentrated flavor and drier texture.

Preparation Position rack in center of oven and preheat to 400°F. Butter 9- by 13-inch baking dish or 2-quart casserole. Line rimmed baking sheet with aluminum foil. Pierce each potato with fork and transfer to baking sheet. Bake until tender, about 50 minutes. Cool until easy to handle. Meanwhile, make streusel: In medium bowl, combine flour, 3/4 cup brown sugar, and 1 stick butter. Rub mixture between fingertips until blended and crumbly. Set aside. Halve potatoes lengthwise and scoop out flesh into large bowl. Add remaining 1/3 cup brown sugar and 3/4 stick butter and mash with potato masher or, for a smoother purée, handheld electric mixer. Spread mixture in prepared dish and cool completely. (Streusel and purée can be made up to 2 days ahead and refrigerated, separately, covered.) Sprinkle streusel over potatoes. Bake until golden brown, about 40 minutes. Let stand 5 minutes before serving. (Completed dish can be prepared up to 1 day ahead and refrigerated, covered. Remove from refrigerator 1 hour before reheating and let come to room temperature. Bake, loosely covered with foil, until heated through, about 25 minutes.) Variation: Sweet potato purée with marshmallows: Omit streusel. Spread purée in baking dish, cover with foil, and bake until heated through, about 30 minutes. Sprinkle top with 3 cups miniature marshmallows and broil until marshmallows are lightly browned, about 1 minute. Serve immediately. Test-Kitchen Tips:•Most American cooks use the terms "sweet potato" and "yam" interchangeably, but there are actually three different types of vegetable referred to by these terms: The true sweet potato (also known as a boniato), available at Asian and Latino markets, has pale yellow flesh, skin with a purplish cast, and a chestnutlike flavor that isn't sweet at all. The true yam, also called a ñame (NYAH-meh), is a large tuber with scaly brown skin that's a staple of Caribbean, African, and Hispanic cuisines. The familiar, bright-orange-fleshed tubers called for in this recipe are a third type, a variety of the sweet potato that are often called "yams" to distinguish them from yellow-fleshed "true" sweet potatoes. The Louisiana, jewel, or garnet varieties will all work well. •While some recipes for sweet potato purée call for boiling the potatoes, roasting gives a much sweeter, more concentrated flavor and drier texture.