Crust
6 ounces saltines
⅛ teaspoon salt
10 tablespoons unsalted butter, melted
¼ cup light corn syrup
Filling
1 (14-ounce) can sweetened condensed milk
4 large egg yolks
¼ cup heavy cream
1 tablespoon grated lemon zest plus 1/2 cup juice (3 lemons)
⅛ teaspoon salt
Topping
½ cup heavy cream, chilled
2 teaspoons sugar
½ teaspoon vanilla extract
FOR THE CRUST: Adjust oven rack to middle position and heat oven to 350 degrees. Combine saltines and salt in food processor and pulse to coarse crumbs, about 15 pulses. Add melted butter and corn syrup and pulse until crumbs are broken down into oatmeal-size pieces, about 15 pulses.
Transfer saltine mixture to greased 9-inch pie plate. Using bottom of dry measuring cup, press crumbs into even layer on bottom and sides of plate, using your hand to keep crumbs from spilling over plate edge. Place plate on baking sheet and bake until light golden brown and fragrant, 17 to 19 minutes.
FOR THE FILLING: Whisk condensed milk, egg yolks, cream, lemon zest, and salt in bowl until fully combined. Whisk in lemon juice until fully incorporated.
With pie plate still on sheet, pour filling into crust (crust needn’t be cool). Bake pie until edges are beginning to set but center still jiggles when shaken, 15 to 17 minutes. Place pie on wire rack and let cool completely. Refrigerate pie until fully chilled, about 4 hours.
FOR THE TOPPING: Using stand mixer fitted with whisk, whip cream, sugar, and vanilla on medium-low speed until foamy, about 1 minute. Increase speed to high and whip until stiff peaks form, 1 to 3 minutes. Spread whipped cream over top of pie. Serve.