Make the crust: Mix the graham cracker crumbs and melted butter in a bowl until it looks like sandy magic. Press into a 9-inch pie pan. Chill in the fridge while you do the next step.
Whip the cream: In a cold bowl, beat the heavy cream until soft peaks form. Set aside.
Mix the filling: In another bowl, whisk together the sweetened condensed milk, lemon juice, lemon zest, and vanilla. You’ll notice it thickens slightly—this is the good stuff happening.
Fold in the whipped cream: Gently fold the whipped cream into the lemon mixture. Go slow; we want fluffy, not deflated.
Assemble the pie: Pour the filling over the chilled crust. Smooth the top with a spatula.
Chill, don’t freeze yet: Refrigerate for at least 4 hours (overnight is even better) until the filling sets. You’re basically practicing patience now.
Decorate: Right before serving, top with berries, candied lemon, or a light dusting of zest.