Place the raisins and 2 tablespoons of rum in a bowl, cover with plastic wrap, and place in the microwave on high for 1 minute. Uncover and set aside to cool.
Beat the egg yolks and sugar in the bowl of an electric mixer fitted with the paddle attachment on high speed for 5 minutes, until very thick and light yellow. Lower the speed to low and mix in the mascarpone until smooth. With the mixer still on low, add 1/2 cup of rum, 1/4 cup of orange juice, the vanilla extract, and the seeds from the vanilla bean. Stir until combined.
Pour the remaining 1/2 cup of rum and remaining 1/2 cup of orange juice in a shallow bowl. Dip one side of each ladyfinger quickly in the rum mixture and place them in one layer in a 9 by 11 by 2-inch rectangular or oval dish. Break the ladyfingers in smaller pieces and dip them in the rum mixture to fill the spaces. Sprinkle half the rum-soaked raisins evenly on top. Pour half the mascarpone mixture over and spread evenly. Repeat the layers of dipped ladyfingers, rum-soaked raisins, and mascarpone mixture. Smooth the top, cover with plastic wrap, and refrigerate for at least 6 hours, but preferably overnight.
Before serving, sprinkle the top with the shaved chocolate and serve cold.