Preheat oven to 350 degrees. Sift cocoa and sugar together. Separate the eggs. Put the yolks and vanilla in large bowl and beat well until thick. In another bowl whisk the egg whites until foamy. Add salt and continue beating until soft peaks are formed. Fold cocoa and sugar into the whites, then gently fold 1/3 cup of egg white mixture into beaten yolks. Thorough- ly butter a 10 x 15-inch cookie sheet and line it with wax paper. Spread the batter evenly in pan. Bake 18 to 20 minutes until knife comes out clean. Sprinkle a clean tea towel with powdered sugar and turn cake out onto it. Remove wax paper and trim off any crisp edges. Roll the cake in the towel from the long end of towel and let rest 1 to 2 minutes. Unroll and let it rest again for a few minutes, then roll it up again and allow it to cool completely. Set ice cream out to soften. Unroll cooled cake; spread evenly with ice cream and roll it back up (without the towel). Dust top with powdered sugar. Keep it in the refrigerator until ready to serve. When ready to cut, serve with Killer Chocolate Sauce.

Killer Chocolate Sauce: Melt butter and chocolate in heavy saucepan over low heat. Add boiling water and stir well. Mix sugar and corn syrup until sauce is smooth. Boil the sauce without stirring for 10 minutes. Remove from heat and cool for 20 minutes, then add vanilla. Spoon the sauce over ice cream cake and serve.