In a large covered saucepan cook sweet potatoes in boiling water about 15 minutes or until tender.
Meanwhile, in a medium mixing bowl combine flour and salt. Using a pastry blender cut in shortening until pieces are pea-size. Sprinkle cold water, 1 tablespoon at a time, over part of mixture. Gently toss with fork just until all dough is moistened. Form dough into ball.
On a lightly floured surface roll dough from center to edge into a 12-inch circle. Transfer pastry to a 10-inch deep-dish pie plate. Trim pastry to 1/2 inch beyond edge of plate. Fold under extra pastry; crimp edge as desired. Line unpricked pastry shell with a double thickness of foil. Bake in a 450 degree F oven for 8 minutes. Remove foil; bake for 4 to 5 minutes more or until set and dry. Set aside. Reduce oven temperature to 400 degrees F.
Drain potatoes. In a large bowl combine potatoes and butter. Beat with electric mixer until smooth. Add sugar, cinnamon, nutmeg, and the dash salt. Beat until combined. Add eggs. Beat on low speed just until combined. Gradually stir in evaporated milk.
Carefully pour filling into prepared pastry shell. Cover edge of pie with foil. Bake in the 400 degree F oven for 10 minutes. Reduce heat to 350 degrees F and bake for 40 to 50 minutes more or until knife inserted in center comes out clean. Cool on wire rack for 1 hour. Serve warm. (Or, cover and refrigerate after 2 hours.) If desired, serve with whipped cream sprinkled with ground nutmeg. Makes 8 servings.
Join the ranks of many southern families who make this nicely spiced pie -- instead of pumpkin -- their holiday dessert.