Combine graham cracker crumbs, sugar, and melted butter in a bowl. Press firmly into a 9-inch pie dish and freeze for 10 minutes.

Whisk together the sweetened condensed milk, fresh lemon juice, and lemon zest in a large bowl until smooth and slightly thickened.

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

Gently fold the whipped cream into the lemon mixture until fully combined. Pour the filling into the prepared crust and smooth the top.

Cover with plastic wrap and freeze for at least 4 hours or overnight until firm. Let sit at room temperature for 5-10 minutes before slicing and serving.