In a small bowl combine raisins and rum. If you can't use rum, soak the raisins in water but I highly encourage you to use rum because it's an essential part.
Separate the eggs and set the egg yolks aside for a moment.
In the bowl of a stand mixer fitted with the whisk attachment add the three egg whites and beat at high speed about 2.5 minutes until stiff peaks form. Don't overbeat the egg whites! Transfer to a bowl and set aside.
Add the three egg yolks, melted butter, vanilla extract, sugar, and a pinch of salt to the (now empty) bowl of your stand mixer, still fitted with the whisk attachment. Combine at medium speed about 2-3 minutes.
On low speed, alternately add flour and milk, a tablespoon of each at a time, until you used up the milk and the flour. Don't overmix. Scrape down the sides and up the bottom of the bowl as needed.
Using a metal spoon or rubber spatula, fold in the stiff egg whites until combined and no big egg white lumps remain. You need to be very gentle and light-handed.
Heat 1 tbsp butter in a 12-inch skillet over medium heat. Pour the batter into the skillet and cook for about 6-7 minutes. After 3 minutes sprinkle the drained raisins over the batter. Use a spoon to peak under the pancake to see if it's golden brown underneath.
When the pancake is golden brown underneath, sprinkle the top with a little bit of sugar. Using a spatula, divide the pancake into quarters and turn the pieces. Add a little bit of butter to the pan while turning the pancake.
Cook for 3-4 minutes until the quarters are golden brown underneath.
Using two spatulas or forks, tear the pancake into bite-sized pieces.
Add 2 tbsp butter and sprinkle 2 tbsp sugar over the pancake pieces. Turn up the heat to medium-high and gently toss the pieces with a spatula for about 3-4 minutes, until the sugar has caramelized.
Sprinkle with confectioners' sugar and serve in the pan with applesauce on the side.