Pulse graham crackers in a food processor until finely ground. Combine with melted butter and sugar, pressing into a pie pan.

Whip heavy cream with powdered sugar until stiff peaks form. In a separate bowl, mix thawed limeade, sweetened condensed milk, and lime zest until combined.

Gently fold the whipped cream into the lime mixture until smooth and well combined.

Pour the filling into the crust, spreading evenly. Freeze uncovered for at least 6 hours until solid.

Thaw the pie at room temperature for about 10 minutes before slicing and serve chilled.