1. Preheat oven to 425°.
2. Combine sugar and cinnamon in a bowl, stirring with a whisk. Set aside 1 tablespoon cinnamon-sugar in a small bowl. Add flour and salt to remaining cinnamon-sugar, stirring with a whisk.
3. Fit one-half of dough into a 9-inch pie plate coated with cooking spray, allowing dough to extend 1/2 inch over edge of pie plate. Sprinkle 2 1/2 tablespoons flour mixture in bottom of prepared crust. Layer one-third of apple slices over flour mixture. Repeat procedure twice; sprinkle remaining flour mixture over apples. Fit remaining half of dough over filling. Press edges of dough together. Fold edges under; flute. Cut several slits in top of dough to allow steam to escape.
4. Combine egg and 1 tablespoon water in a small bowl. Brush egg mixture over dough; sprinkle with reserved cinnamon-sugar. Bake at 425° for 30 minutes or until apples are tender and crust is golden. Remove from oven; cool completely on a wire rack.