Combine the graham cracker crumbs, melted butter, and granulated sugar in a large mixing bowl. Stir until well combined and the mixture resembles wet sand. Press the mixture evenly into the bottom and up the sides of a 9-inch pie pan to form a crust. Refrigerate while preparing the filling.

In a mixing bowl, whisk together the sweetened condensed milk, fresh lemon juice, lemon zest, and vanilla extract until smooth and well combined.

In a separate bowl, beat the heavy whipping cream with an electric mixer until soft peaks form.

Gently fold the whipped cream into the lemon mixture, ensuring it is fully incorporated and the filling is light and airy.

Pour the lemon filling into the prepared graham cracker crust, smoothing the top with a spatula.

Cover the pie with plastic wrap and refrigerate for at least 4 hours, or until set. For best results, allow the pie to chill overnight.

Once set, garnish with additional lemon zest or fresh berries if desired, before slicing and serving.

Store any leftover pie in the refrigerator, covered with plastic wrap, for up to 3 days.