Combine first 5 ingredients. Toss together pears, lemon juice, and vanilla in a large bowl. Add sugar mixture, tossing to coat.
Roll 1 piecrust to press out fold lines. Place piecrust on a nonstick aluminum foil-lined baking sheet. Spoon pear mixture in center of pastry, leaving a 3-inch border.
Combine 1/3 cup flour, 1/4 cup brown sugar, and 1/4 teaspoon cinnamon in a medium bowl; cut in butter with a pastry blender or fork until mixture is crumbly. Sprinkle over pear mixture. Lift pastry edges, and pull over pear mixture, fluting edges. Press edges gently to secure.
Roll remaining piecrust to press out fold lines; cut out leaves with a 2 1/2-inch leaf-shaped cutter. Arrange leaves over pear mixture; brush with egg white.
Bake at 425° for 10 minutes. Reduce heat to 350°; bake 35 more minutes or until golden and bubbly. Let stand 20 minutes before serving. Serve with sweetened whipped cream.
Tip: If you don't have leaf-shaped cutters, any shaped cutters will work. Your piecrust will slip down during baking, so make sure it's fitted snug up over your pear mixture before baking.