Sweet Potato Pie
["2 lb. sweet potatoes (about 3 medium)", "3/4 c. packed brown sugar", "1/4 tsp. all-purpose flour", "2 tsp. grated orange peel", "1 tsp. pumpkin pie spice", "1 tsp. vanilla extract", "1/8 tsp. salt", "1 c. fat-free milk", "1/2 c. egg substitute", "1 unbaked pastry (9 inches)", "1/2 c. reduced-fat whipped topping"]
["Bake sweet potatoes at 350\u00b0 for 1 hour or until very soft. Cool slightly. Cut potatoes in half; scoop out the pulp and discard shells. Place pulp in food processor or blender; cover and process until smooth."]
["sweet potatoes", "brown sugar", "all-purpose flour", "pumpkin pie spice", "vanilla extract", "salt", "milk", "egg substitute", "pastry", "topping"]