Unroll pie crust on work surface. Cut 2 (5-inch) rounds from pie crust. Wrap remaining pie crust tightly in food safe plastic wrap and refrigerate for future use. Place each round over pie filling, draping over edges of custard cups. Lightly brush pie crust with egg white. Cut slits on top of each. Sprinkle with 1/2 teaspoon sugar. Place custard cups on cookie sheet.