In a food processor, pulse the graham crackers until they are fine crumbs. Add the sugar and melted butter. Pulse until evenly combined and resembling damp sand.
12 sheets graham crackers, 3 tablespoon sugar, 7 tablespoon butter
To form the crust, dump ⅔ of the crumbs in the bottom of a 9-inch deep dish pie pan. Using your fingers or a tamper, press the crumbs firmly into the side. Then add the remaining crumbs and press firmly into the bottom of the pan.
In a stand mixer fitted with whisk attachment or hand beaters, whip the heavy cream and powdered sugar on high until stiff peaks form, about 6-7 minutes.
1½ cups heavy cream, ½ cup powdered sugar
In a separate bowl, thoroughly combine the frozen concentrate, sweetened condensed milk, and orange zest. Using a rubber spatula, gently fold the cream into this mixture, continuing to fold until it is thoroughly combined and no white streaks remain.
6 oz (about ¾ cup) frozen orange juice concentrate, 14 oz sweetened condensed milk, ½ orange
Pour the filling into the prepared pie crust. Smooth out the top or add a design (see post for ideas). Then freeze uncovered for at least 6 hours. Once frozen thoroughly, cover with plastic wrap and leave in the freezer until ready to serve.
To serve, thaw for about 10 minutes to make it easier to cut. Enjoy!