Preheat oven to 375 degrees F.
On a lightly floured surface, roll out the pie crust to fit a 10-inch pie pan. Fit inside the pan and set aside.
In a large mixing bowl, combine the mashed sweet potatoes, Steen's syrup, spices, 1 egg, and 1/2 teaspoon of the vanilla and mix well. Pour the filling into the unbaked pastry shell. Spread the pecan pieces evenly over the filling.
In another large bowl, beat the remaining 4 eggs. Add the remaining 1 teaspoon vanilla, granulated sugar, brown sugar, corn syrup, and salt and stir to blend. Pour over the pecans and bake until the filling is set and the pastry is golden brown, about 1 hour.
Remove from the oven and cool on a wire rack for 1 hour before serving. Garnish with chocolate curls, whipped cream, and confectioners' sugar.
Yield: 1 (10-inch) pie; 8 servings