In a small bowl, soak ¼ cup raisins in 2 tbsp rum for about 15 minutes. Then, strain the raisins out of the rum and discard the rum. Set the raisins aside.
In a medium bowl, mix the 3 egg yolks with the ½ tsp vanilla, ¾ cup milk, lemon zest from one lemon, and a pinch of salt. Add the 1 cup flour and 2 tbsp of granulated sugar. Whisk until combined.
Use an electric hand mixer or stand mixer to whisk the 3 egg whites to soft peaks. Add ½ tbsp of granulated sugar and continue mixing until stiff peaks form.
Add the egg whites into the batter and gently hand mix with a rubber spatula until the whites from the whites blend into the batter.
Melt 2 tbsp butter in a large frying pan. Once the butter begins to bubble, add the batter into the pan.
Sprinkle the top of the batter with the rum-soaked raisins and the remaining ½ tbsp of granulated sugar. Cover with lid and allow it to cook for 3-5 minutes.
Once the bottom is cooked, flip the pancake. Continue cooking until the batter is cooked all the way through.
Once cooked, leave the pancake in the pan but use a spatula to cut the pancake into uneven bites.
Top the shredded pancake with powdered sugar and serve with a side of applesauce or plum preserves. Serve warm in the pan.