Adjust oven rack to highest position. Preheat 375~.

Grease a jelly roll pan 15 1/2x10 1/2, line with waxed paper, grease lightly. In a large mixer bowl, combine egg whites and salt, beat until foamy. Gradually beat in 1/4 cup sugar, and vanilla. Beat until stiff, but not dry. In small bowl, beat egg yolks and rest of sugar until very thick and lemon colored(5-10 minutes) Sift together 1/4 cup cocoa, flour and cornstarch.

Fold into egg yolk mix, then flod mix into beaten whites, Pour in prepared pan, spread evenly. Bake 12-15 minutes, until lightly browned and center is springy to the touch. Meanwhile, sprinkle a towel with confectioner's sugar. Invert cake onto towel, and peel off waxed paper. While still hot, roll up cake with twol, jelly roll fashion, from the long side. Let stand 1 minute, then unroll to let steam escape, then re-roll with towel. Cool compeltely on wire rack.

Unroll, and spread with softened ice cream. Reroll, cover and freeze until firm. Sprinkle with 1 tsp cocoa just before serving.