This dish is called Kaiserschmarrn, which translates to something like "Emperor's Mess." The legend says that Emperor Francis Joseph I was having dinner with his wife (who was on a diet at the time). When this heavy dessert was served and she couldn't eat it, the emperor supposedly said "gimme that mess" -- hence the name.
For the pancake: Soak the raisins in the rum in a small bowl until slightly softened.
Preheat the oven to 400 degrees F (see Cook's Note).
Mix together the flour, milk, vanilla and salt in a large bowl until smooth. Mix in the egg yolks. In a separate bowl, whip the egg whites and granulated sugar to stiff peaks. Fold the egg whites into the flour mixture.
Melt the butter in a large cast-iron pan over medium heat and pour the batter into the pan. Take the raisins out of the rum and sprinkle them over the batter. Transfer the pan to the oven and bake until the pancake is a nice light brown color, about 15 minutes. Remove the pancake from the pan and set it aside.
For the caramel: Heat the butter and granulated sugar in the pancake pan over medium heat until the sugar caramelizes, 3 to 4 minutes. Rip or cut the pancake into bite-size pieces and toss them in the caramel.
Transfer the pancake pieces to a serving plate and dust confectioners' sugar on top. Serve with applesauce and/or stewed plums on the side.
If your oven has a setting for cooking with both upper and lower heat, use it setting here.