When I set out to make this pie, I assumed its persuasive texture and flavor were the invention of Nabisco's test kitchen. The company first issued a back-of-the-box recipe for it in 1935, a year after the introduction of the Ritz cracker. But, as it happened, thrifty cooks had long since discovered that crackers, when combined with cream of tartar, lemon juice, cinnamon, and sugar, bore an uncanny resemblance to apple filling. Civil War soldiers used their hardtack rations to simulate homemade apple pies, and even by that time the recipe was on its way west. As the food historian Barbara Haber told me, "We may never know who was the first person to substitute crackers for apples, but my money is on some lady in a poke bonnet in a covered wagon."