I got this recipe here. These were a HUGE hit at Thanskgiving. The streusel topping is the perfect finish.
3 pounds sweet potatoes (about 3 large), peeled, cut into 1-inch pieces
1/4 cup (1/2 stick) butter, room temperature
1/4 cup sugar
1 cup half and half
1/3 cup chopped crystallized ginger (about 1 1/2 ounces)
1 teaspoon vanilla extract
Topping 1 cup (packed) golden brown sugar
1/2 cup all purpose flour
1/2 cup (1 stick) butter, room temperature
1 cup chopped pecans (I left these out)
1 cup sweetened flaked coconut
Butter 13x9x2-inch glass baking dish. Cook sweet potatoes in large pot of boiling salted water until tender, about 8 minutes. Drain; return to same pot. Stir potatoes over medium-high heat until excess liquid evaporates. Remove from heat. Add butter and sugar and mash potatoes until almost smooth. Mix in half and half, eggs, ginger and vanilla. Season with salt. Spread in prepared dish (filling will be about 1 inch thick).
Rub together sugar, flour and butter in medium bowl until moist crumbs form. Mix in pecans and coconut. (Filling and topping can be prepared 1 day ahead. Cover separately and refrigerate.)
Preheat oven to 350°F. Sprinkle topping over filling. Bake until filling is set and topping is brown, about 60 minutes. Let stand 10 minutes. Cut into squares and serve.