Step 1Spread the crackers in a single layer on a piece of wax paper. Cover them with another piece of wax paper. Roll a rolling pin over them, pressing down as you roll so the crumbs are reduced to fine-size crumbs. Measure the crumbs; you should have 1 1/2 cups.
Step 2Stir the crumbs and the sugar together in a bowl. Pour the melted butter into the crumb mixture, and, using your hands, stir and toss so the butter is well mixed into the crumbs.
Step 3Remove 1/4 cup of the crumbs and set aside to sprinkle on top of the pie. Press the crumbs into the bottom and sides of a 9-inch pie pan. Refrigerate the crust while you make the filling.
Step 1Heat the oven to 325 degrees.
Step 2Place the egg yolks in a mixing bowl and, using a fork, stir briskly until well blended.
Step 3Grate the rind off of the lemons and add it to the yolks. Squeeze the juice of both lemons, remove any seeds, and add the juice to the yolks. Beat until thoroughly blended (you can't overbeat). Stir in the condensed milk and salt until well blended.
Step 4Beat the egg whites until they are stiff enough to hold a peak when you lift some whites on the egg beater. Fold the whites into the yolk mixture until the mixture is all one color. Spoon into the crumb-lined pan and sprinkle the reserved 1/4 cup of crumbs evenly over the top.
Step 5Bake the pie until a toothpick inserted in the middle comes out clean, about 50 minutes. Serve slightly warm or cold.