Break up the graham crackers; place in a food processor and process to crumbs. If you don’t have a food processor, place the crackers in a large plastic bag; seal and then crush the crackers with a rolling pin.
Graham Cracker Crust:
1/3 of a 1-pound box graham crackers
5 tablespoons melted unsalted butter
1/3 cup sugar
Filling:
3 egg yolks
2 teaspoons lime zest
1 (14-ounce) can sweetened condensed milk
2/3 cup freshly squeezed Key lime juice, or store bought
Topping:
1 cup heavy or whipping cream chilled
2 tablespoons confectioners’ sugar