Preheat oven to 425°.
Combine flour and salt; cut in shortening with pastry blender until mixture is crumbly. Sprinkle water, 1 tablespoon at a time, over surface of mixture. Stir with a fork until dry ingredients are moistened.
Shape dough into a ball. Roll into a 10-inch circle on a floured surface. Combine sweetener and next 3 ingredients; sprinkle over apple, and toss.
Spoon mixture into a 9-inch pieplate; sprinkle with lemon juice. Place pastry over apple mixture; fold edges under, and crimp. Coat with cooking spray.
Bake at 425° for 25 minutes. Serve warm. Top with ice cream, if desired (ice cream not included in analysis).
For testing, we used Splenda as the calorie-free sweetener.