Preheat the oven to 350ºF. Use a food processor or rolling pin to crush the vanilla wafers into very fine, even crumbs. Add the melted butter and sugar and stir until everything is very well combined.
Press the butter crumb mixture into a 9-inch pie plate and use a flat bottomed glass to compress the mixture until solid. Bake the crust for 10 minutes in the preheated oven. After baking, transfer the crust to the refrigerator to cool.
Zest and juice the lemons. You'll need ½ cup lemon juice and 1 Tbsp zest. Slice any leftover unjuiced portions of the lemon to use as garnishes.
Add the sweetened condensed milk to a bowl along with the lemon juice, lemon zest, and vanilla extract. Whisk until everything is well combined.
In a separate bowl, whip 1 cup heavy whipping cream until it forms stiff peaks.
Add ¼ of the lemon and sweetened condensed milk mixture to the whipped cream and gently fold until combined. Repeat with ¼ of the lemon mixture at a time until all of it has been folded into the whipped cream.
Pour the lemon cream filling into the cooled pie crust and refrigerate until completely chilled (about two hours). Slice into 8 pieces and serve.
*For a softer crust, just press the filling into the pie plate without baking. You can use either vanilla wafers OR graham crackers for this pie crust. You can use any prepared store-bought crust in place of the crust recipe listed here.