Line a 9-inch pie pan with 1 rolled-out crust; trim edges, leaving a -inch overhang. Place in freezer until ready to fill, or at least 20 min.

Heat oven to 425 degrees F with rack in the bottom third. Cut apples into -inch-thick slices and toss in a large bowl with lemon juice, cinnamon, nutmeg and cornstarch. Add 1/2 cup Salted Caramel Sauce and toss to combine. Pour apples into chilled pie shell and return to freezer.

Roll remaining disk of dough to a 13-inch circle. Use a paring knife to cut slits or small designs on the top. Brush rim of bottom crust with egg wash and cover with second dough round, sealing the edges. Trim edges as necessary and crimp. Brush pie with extra egg wash and sprinkle with crystal sugar; freeze pie again until crust is cold, about 20 min.

Bake pie on a foil-lined baking sheet until crust begins to brown, about 20 min. Reduce heat to 375 degrees F and bake until crust is golden and juices bubble, 50 to 60 min more. (If crust browns too quickly, tent pie with foil.) Cool pie and serve slices with Salted Caramel Sauce.