Lemon ice box pie is a chilled, creamy, and tart American dessert, often credited as having roots in the traditional cuisine of the American South. The dessert traditionally includes filling ingredients such as lemon juice and condensed milk in a pressed crumb crust. Typically, the pie requires no cooking, with fillings allowed to set in the refrigerator until firm. Characteristically, lemon ice box pie bears a strong resemblance to key lime pie, substituting lemons or lemon juice instead of limes.
Ice box pies are cream-type pies, so named for the need to keep such pies chilled in an ice box or refrigerator. Stories regarding the origins of lemon ice box pie typically place the dessert's creation somewhere in the southern United States, although many recipes originated in other areas as well. Since the recipe requires refrigeration, it is unlikely that any ice box pie recipe existed prior to the invention of ice boxes in the early 1800s at the earliest, and more likely came after the invention of electric refrigerators in the early 1900s.
Variations on lemon ice box pie recipes are numerous. Some recipes use lemonade instead of lemon juice, or add additional ingredients such as cream cheese, whipped cream toppings, or nuts or bits of lemon and other citrus fruits. No matter the specific ingredients or recipe used, pies typically require continuous refrigeration to prevent the filling from melting or separating at room temperature. Thickening agents, such as gelatin, are sometimes used to ensure pies set firm enough to slice and can withstand longer exposure to room temperature.
Recipes for lemon ice box pie and similar desserts are a favorite for young and beginner cooks, due to the ease with which such pies can be made. All that is required is the right ingredients, a way to whip the filling, and a crust. Graham cracker crumbs mixed with butter is the typical crust for a lemon ice box pie, requiring the maker to simply mix and press the crumbs into a pan. Fillings are poured into the crust after a short period of whipping. Once assembled, a lemon ice box pie only takes a short time in the refrigerator to set up enough to serve.
Since lemon ice box pies and similar desserts are chilled, these desserts are more commonly served during warm summer months. In fact, the ease of preparation, lack of cooking required, and chilled serving requirements illustrate why this particular dessert has enjoyed a long history as a Southern favorite. Prior to World War II, few Southern farms had electricity, relying on ice boxes and various cool desserts to alleviate the characteristically high heat and humidity of summers.