Soak the raisins in rum for at least 40 minutes.  Strain, reserving the rum aside for buttered rum sauce, recipe below. 

Soak the raisins in rum for at least 40 minutes.  Strain, reserving the rum aside for buttered rum sauce, recipe below. 

Combine egg yolks and sugar in a large mixing bowl.  Beat until pale yellow and as they start to thicken (about 2 minutes with a handheld mixer on medium speed).  Use a rubber spatula to occasionally reincorporate parts of the mixture that may stick to the side of the bowl.  Add the vanilla extract, almond extract, salt, lemon zest, and milk.  Slowly add in the flour (one to two tablespoons at a time) until completely incorporated.  Stir in the raisins, making sure to distribute them evenly.  Place the batter mixture aside.

In a separate mixing bowl, add the cream of tartar to the egg whites, beating the whites to stiff peaks.  Be careful not to overbeat them — if they begin to look speckled, you’ve gone too far. Take one fourth of the egg whites and add them to the batter mixture, mixing together well.  Then, gently fold the remaining of the beaten egg whites, one fourth at a time, into the batter mixture, taking great care not to overfold.

Add a tablespoon of butter to a 12-inch skillet over medium heat.  Spread the melted butter around the skillet.  Pour the batter into the skillet, making sure the raisins are distributed evenly as you pour.  Allow to cook undisturbed on one side until golden brown (about 3-4 minutes), then flip to the other side.  If there’s too much batter for you to flip it all at once, cut it into pieces and then flip each individual piece. Don’t worry if it falls apart slightly — you’re going to break it up later anyway.  The most important thing is to make sure all the batter is now cooking, as no one wants raw batter.  When the other side is golden brown, break all of the pancake into inch-long pieces, where the asymmetry is part of the beauty of the dish.  Take the skillet off the heat.  Add another 3 tablespoons of butter and the confectioner’s sugar evenly throughout the dish.  Return to medium heat and cook for around 2 minutes, tossing the pancake bits as they cook. 

Plate the Kaiserschmarrn and dust with powdered sugar.