On one recent Tuesday night, I texted my friend Katie and asked her to come over to make some fortune-telling flatbread. When she showed up, wary but game, I explained a bit more. We were going to bake a dumb cake. The name, by the way, isn’t meant to describe a poorly-thought-out pastry. Instead, it was the main event of a baking ritual conducted by young, unmarried women across the United Kingdom and North America from the 1700s up to the mid-1900s. Universally, the goal was the same: to discover…