Icebox cakes are an unusual style of cake that uses the refrigerator instead of the oven to bring all the elements of the cake together. The cakes are constructed by layering cookies with whipped cream, sweetened condensed milk, custard and other similar components, then refrigerated until the cookies soften into a cake-like consistency and all the flavors of the dessert meld together. The cookies used are typically graham crackers or chocolate wafer cookies. The result is a beautifully layered dessert that is very cake-like, but involves no baking at all.
Icebox cakes first became popular in the US in the 1920s and the recipe developed out of other chilled, layered desserts such as trifles. During that time period, most homes, especially in large cities, were equipped with iceboxes and the availability of iceboxes helped popularize this style of cake. In the 1930s and beyond, refrigerators replaced traditional iceboxes, but the name of the cake remained.
Icebox cakes are usually constructed in a baking dish, where the sides of the pan make it easy to layer together all the components, though the cakes can be assembled to be free-standing, as well. Like traditional cakes, they come in a wide variety of flavors and you can get very creative with the elements that you put in yours. These recipes will get you started.