Unroll piecrust onto a lightly floured surface. Pat or roll into a 12-inch circle. Place piecrust on an aluminum foil-lined 12-inch pizza pan. Brush crust with half of egg white.
Combine 3/4 cup sugar, cornstarch, and cinnamon in a medium bowl. Add apples, and toss to coat; spoon into center of prepared piecrust, leaving a 2-inch border. Fold piecrust border up and over apples, pleating as you go, leaving an opening about 8 inches wide in center. Brush crust with remaining egg white; sprinkle with 1 teaspoon sugar.
Bake at 425° on bottom oven rack for 20 to 25 minutes or until apples are tender and crust is golden. Cool 15 minutes before serving.
Mini Rustic Apple Pies: Unroll 2 piecrusts on a floured surface; roll each into a 14-inch circle. Cut 3 (6 1/2-inch) circles from each piecrust, rerolling scraps as needed. Brush with half of egg white as directed. Prepare apple mixture as directed in Step 2; spoon about 2/3 cup apple mixture into center of each circle, leaving a 1 1/2-inch border. Fold border up and over apples, pleating as you go, leaving an opening about 2 inches wide in center. Brush piecrusts with remaining egg white; sprinkle evenly with 1 teaspoon sugar. Proceed with recipe as directed. Makes 6 servings. Prep: 30 min., Bake: 25 min., Cool: 15 min.