Line a 15x10x1-inch baking pan with 18-inch-wide foil, extending the foil up over the edges of the pan; set aside. For dough: In a large bowl, stir together the 2-1/4 cups flour and the salt. Using a pastry blender, cut in shortening until mixture resembles coarse crumbs. Sprinkle 1 tablespoon of the cold water over part of the flour mixture; gently toss with a fork. Push moistened dough to side of bowl. Repeat, using 1 tablespoon cold water at a time, until all of the flour mixture is moistened. Using your fingers, gently knead the dough just until a ball forms.
Preheat oven to 375°F On a lightly floured surface, roll dough into a 19x13-inch rectangle. Wrap it around the rolling pin; unroll it into the prepared baking pan. Ease dough into the pan and up the sides, being careful not to stretch it. Trim dough to 1/2 inch beyond edge of pan. Fold dough edge over and flute as desired.
In an extra-large bowl, combine sugar, the 1/3 cup flour, and the cinnamon; add apples. Toss lightly until apples are coated. Spoon apple mixture into dough-lined pan; spread evenly. Sprinkle with Crumb Topping (pan will be full).
Bake for 40 to 45 minutes or until apples are tender. If necessary to prevent overbrowning, cover top with foil for the last 5 to 10 minutes of baking. Cool slightly in pan on a wire rack.
Serve warm or cool completely. Cut into rectangles. Makes 25 servings.
In a large bowl, stir together quick-cooking rolled oats, packed brown sugar, and all-purpose flour. Using a pastry blender, cut in butter until topping mixture resembles coarse crumbs. Stir in chopped pecans.
To Bake Ahead:
Bake and cool as directed. Cover and let stand at room temperature for up to 24 hours; or chill for up to 3 days. Return to room temperature before serving.