Preheat oven to 375 degrees. In a large bowl, combine yams, condensed milk, eggs, spices, and salt. Beat at medium speed until smooth. Pour into unbaked 9 inch pastry shell. Bake for 50 minutes or until knife inserted in center comes out clean. Let cool slightly. Arrange pecan halves in circle. Set aside.
In a small saucepan, combine dark brown sugar and whipping cream. Cook over medium heat, stirring constantly until sugar dissolves. Reduce heat and simmer 5 minutes. Let cool 5 minutes. Spoon over pie.
Refrigerate any leftovers.