Recipes from the Great Depression carry reminders of how difficult the period was for the average American. From Depression pie—where oats make for a poor man’s substitute for pecans—to mock apple pie—in which cinnamon-scented Ritz crackers stand in for fruit—the defining feature of most of these confections is what they lack. Even among the genre of desserts known as “desperation pies,” “hard times pie” seems particularly dire. Its other moniker, “water pie,” sounds like a practical joke or urban myth. Like stone soup, it implies conjuring something from nothing. The…