Position a rack in the lower third of the oven and preheat oven to 375 degrees F. Grease a 17 by 11-inch jellyroll pan, and spread with parchment paper, leaving a 2-inch overhang on the short sides. Grease the paper and set aside.
Into a small bowl, combine the cake flour with the baking powder and salt.
Whip the eggs until foamy, then add the sugar and continue to beat until the eggs are airy and have tripled in volume, 4 to 5 minutes. Add the vanilla extract. Sift about one third of the flour mixture into the batter, folding carefully with a rubber spatula. Sift and fold in the remaining flour in 2 more additions without over mixing.
Gently pour the batter down the center of the prepared pan, spreading evenly with a spatula. Bake until the cake springs back when pressed with a finger, 5 to 7 minutes.
Gently lift the cake off of the pan and let rest on a rack for 5 minutes. Turn the cake out onto a sheet of wax paper and slowly pull away the parchment paper.
Spread the softened ice cream in an even layer over the surface of the cake, leaving a 1/2-inch border along the top and bottom. Starting with the end closest to you, begin rolling up tightly. Wrap in the wax paper, then in plastic wrap, and freeze until firm.
Carefully unwrap the cake and set on a serving platter. Drizzle, if desired, with the chocolate sauce and serve.
Yield: 10 to 12 servings