Preheat the oven to 400 degrees. PIE: Combine the first measure of flour, salt and shortening using a pastry blender until the mixture resembles coarse crumbs. Stir in the water a little at a time, using a fork, and form the dough into a ball. Roll out the pastry dough on a lightly floured board. Roll to an 11" or 12" diameter. Fit into a 9" pie pan and flute the edges. Combine the sugar, the second measure of flour, the cinnamon, the nutmeg and the lemon juice in a large bowl. Toss the apple slices in the mixture. Arrange the apple slices in the pie crust. TOPPING: Combine the sugar and flour in a bowl and cut in the butter using a pastry cutter. Sprinkle the topping over the apple filling. Place the pie in the LARGE paper bag. Place the paper bag on a baking sheet and loosely fold the open end of the bag under. Bake until the apples are tender (50-60 minutes). Carefully remove the pie from the bag CAUTION: WATCH OUT FOR THE STEAM COMING OUT OF THE BAG! Serve warm with generous portions of vanilla ice cream.