This pie is surprisingly easy to make but looks and tastes very impressive. If you cannot find Petit Buerre cookies, you can use graham crackers.
Put the lemon peel in the work bowl of a food processor fitted with the metal blade. Add the lemon juice and the condensed milk and pulse to mix, set aside to thicken.
Adjust the oven rack to the center height. Mix crust ingredients and press into a 9-inch pie plate. Bake until lightly brown, about 15 minutes. Cool for 20 minutes on rack.
Pour filling into the cooled crust, bake until the center is set. It may still be slightly "wiggly", but firm, about 15-17 minutes. Cool to room temperature on a rack, refrigerate (well-wrapped) until serving time.
Whip cream to soft peaks. Add confectioner's sugar slowly, and continue whipping until just stiff. Refrigerate for up to 2 hours or freeze. Serve dollops of the cream on each slice of pie.
A novel method to produce cracker or cookie crumbs, if you find yourself with few kitchen implements, was devised by my husband: put the crackers or cookies in several zippered, heavy plastic bags. Put this package in front of one of the front wheels of your car (Ed recommends a Toyota Corolla), and drive back and forth over it. Don't worry about a few pieces of cracker or cookie which might not be fully "crumbed."