Preheat oven to 450 degrees F. Line a large roasting pan or two 15x10x1-inch baking pans with parchment paper or foil; set aside.
In an extra-large bowl combine melted butter and cinnamon. Add apples; toss gently to coat. Spread apple mixture evenly in prepared pan. Roast, uncovered, for 7 to 10 minutes or until edges start to brown, stirring once halfway through roasting. (If using two pans, roast one pan at a time.) Return apple mixture to same bowl; cool. Reduce oven temperature to 375 degrees F.
Meanwhile, prepare Oat Pastry. On a lightly floured surface, slightly flatten one portion of dough. Roll dough from center to edge into a 12-inch circle. Wrap pastry circle around rolling pin; unroll into a 9-inch pie plate. Ease pastry into pie plate without stretching it. Trim pastry even with rim of pie plate.
For filling, in a small bowl stir together brown sugar, flour, and salt. Sprinkle over apple mixture; stir gently to combine. Transfer to pastry-lined pie plate.
Roll remaining dough into a 14-inch circle. Cut slits in pastry to allow steam to escape. Place pastry on top of filling. Trim pastry to 1/2 inch beyond edge of pie plate. Fold top pastry under bottom pastry. Crimp edge as desired. In a small bowl combine egg and the water; brush mixture over pastry. To prevent overbrowning, cover edge of pie with foil.
Place pie on a baking sheet lined with foil. Bake for 30 minutes. Remove foil from pie. Bake for 35 to 40 minutes more or until pastry is golden and filling is bubbly. Cool slightly on a wire rack. While pie is still warm, drizzle with some of the caramel topping. Cool completely on rack. Serve with remaining topping.
In a medium bowl stir together flour, oats, and salt. Using a pastry blender, cut in shortening until pieces are pea-size. Sprinkle 1 tablespoon cold water over part of the flour mixture; toss gently with a fork. Push moistened dough to side of bowl. Repeat with additional cold water, 1 tablespoon at a time, until all of the flour mixture is moistened. Divide in half; shape each half into a ball.