Preheat oven to 350 degrees F.
Butter a 12 by 16-inch baking tray. Line with parchment paper and brush again with butter.
In a mixing bowl, whip the egg yolks with 1/4 cup sugar until ribbony and light in color. Reserve. In another mixing bowl, whip the egg whites to soft peaks. Slowly add the remaining 1/4 cup sugar and continue to whip to medium peaks. Sift the flour again. With a rubber spatula, fold half of the flour mixture into the yolk mixture. Fold in 1/2 of the egg white mixture. Then fold in the remaining 1/2 flour mixture. Lastly, fold in the remaining 1/2 egg white mixture. Pour the batter into prepared baking tray and with an offset spatula, carefully spreading the batter to fill the tray. Bake for 12 to 15 minutes until done and golden in color. Remove from the oven and allow to cool to room temperature. Use as needed. This can be made up to 2 weeks in advanced, wrapped in plastic wrap and foil and stored in the freezer.
In a medium bowl, whisk together the egg yolks and sugar. Add the Marsala and brandy. Place over a double-boiler and cook until mixture reaches 160 degrees F. Continue to cook mixture for another 5 minutes, until the mixture resembles a thick paste (this is a sabayon). Remove from the double-boiler and cool mixture over ice bath, until room temperature. Whip the mascarpone cheese to soft peaks. Fold into the cooled sabayon until well incorporated. Use as layers in the tiramisu or as needed. Can be made up to 4 hours ahead.
Brew fresh espresso. To 1 cup of hot espresso, add the brown sugar, sugar, lemon juice and vanilla extract. Stir until dissolved.
Assembly: Divide the sheet of ladyfinger into 2 (8 by 10-inch) sheets. Divide espresso syrup into 2 portions. Divide the mascarpone cream into 3 portions. To assemble. spread the first portion of the mascarpone cream at the bottom of a deep (8 by 10-inch) mold topped with 1 sheet of ladyfinger. Pour 1 portion of espresso syrup on to layer of ladyfinger until soaked. Repeat process. Lastly, top with the remaining mascarpone cream and cover with grated chocolate. Cover mold and refrigerate at least 2 hours before serving.
Recipe courtesy of Wolfgang Puck, 2002