Unfold pie crust onto baking sheet and make any necessary repairs. Brush crust with egg white. Sprinkle with 1 tablespoon sugar mixture. Sprinkle evenly with remaining sugar mixture. Fold the 1-inch edge over apples and crimp edges where necessary.
Dot apples with butter.
Brush crust with remaining egg white. Bake 15 minutes. Reduce heat to 375 degrees. Bake 15 to 18 minutes longer, or until crust is browned and apples are softened. Transfer to rack.