1 12 cups graham cracker crumbs (10 to 12 full-size crackers)
2 tablespoons ground cinnamon
14 lb unsalted butter, melted and cooled
2 (14 ounce) cans sweetened condensed milk
4 large egg yolks
12 cup lemon juice
To make the crust: In a medium bowl, blend together the crumbs, cinnamon, and butter using a handheld mixer until fully incorporated. Scrape the mixture into a 9-inch pie pan. Press the mixture firmly onto the base and up the sides of the pan, forming a uniform crust about 1/4-inch thick. Refrigerate until ready to use. To make the filling: In a medium saucepan, preferably nonstick, whisk together the milk, egg yolks, and lemon juice until smooth. Cook the custard over medium heat until very hot to the touch, about 10 minutes, stirring occasionally with a wooden spoon. Do not allow to boil. Strain the custard through a sieve into the prepared pie shell. Refrigerate uncovered at least one hour, or until set. Cover with plastic wrap and chill completely, at least another hour.