How to Make It
Heat oven to 350° F. In a food processor, process the gingersnaps until fine crumbs form. Add the butter, granulated sugar, and ½ teaspoon of the salt and pulse until moistened. Press the mixture firmly into the bottom and up the sides of a 9-inch pie plate, using a straight-sided dry measuring cup to help. Place on a rimmed baking sheet and bake until the edges are dry and set, 16 to 18 minutes. (Note: The bottom will still appear moist and soft but will become firmer as it cools; this is a crunchy cookie crust, not a soft, graham cracker-style one.) Let cool.
In a medium bowl, whisk together the eggs, condensed milk, lemon zest and juice, and the remaining ½ teaspoon of salt. Pour the mixture into the crust and bake until set in the center, 18 to 20 minutes. Let cool and then refrigerate until firm, at least 2 hours.
Using an electric mixer, whip the cream and confectioners’ sugar on medium until soft peaks form, 2 to 3 minutes. Spread on the pie, sprinkle with the additional zest, and serve immediately.