Preheat oven to 400 degrees F. Line a baking sheet with parchment paper; set aside. On a lightly floured surface, unfold pastry. Roll into a 14x11-inch rectangle; trim to a 12x10-inch rectangle. Place on the prepared baking sheet. Brush edges of pastry with egg white. Cut 1/2-inch strips from pastry trimmings. Place strips on edges of pastry rectangle, pressing to form raised rim; trim ends. Brush edges again with egg white. If desired, decorate edges with cutouts from pastry trimmings and brush cutouts with egg white. Prick center of pastry rectangle with a fork.
For topping, in a small bowl stir together flour, granulated sugar, brown sugar, crystallized ginger, and lemon peel. Cut in butter until pieces are pea-size.
Sprinkle half of the topping over center of pastry rectangle. Arrange pear slices on tart, overlapping slightly. Sprinkle with remaining topping.
Bake for 15 to 18 minutes or until pastry is golden and pear is tender. If desired, top each serving with whipped cream. Serve warm.