From my favourite church cookbook, where all the recipes are tried and true! **Like most of the reviews state, if you don't want to fight with the pastry to make it fit a cookie sheet - make 1.5x the dough recipe or use a smaller pan.
Mix flour and salt and cut in shortening. Add egg and milk mixture and mix till it forms a ball. Divide dough in half. Roll first half in 17 x 12 inch rectangle. Place in cookie sheet and bring pastry up sides.
Cover pastry with apples and sprinkle with sugar and cinnamon (homemade chunky applesauce also works well).
Roll out second half of dough and place on top of apples. Moisten edges with milk and pinch together.
Beat egg white until stiff and brush on crust. Bake at 400°F for 1 hour.
Mix glaze ingredients together and brush on crust.