Directions

1. In a large mixing bowl, beat egg yolks until thick and lemon-colored. Gradually beat in 1/4 cup sugar and vanilla. In a small mixing bowl, beat egg whites until soft peaks form. Gradually add remaining sugar, beating until stiff peaks form. Fold into egg yolk mixture. Combine the flour, baking powder and salt; fold into egg mixture.
2. Line a greased 15-in. x 10-in. x 1-in. baking pan with waxed paper and grease the paper. Spread batter evenly into pan. Bake at 375 degrees F for 12-15 minutes or until top springs back when lightly touched. Cool for 5 minutes. Turn cake onto a kitchen towel dusted with confectioners' sugar. Gently peel off waxed paper. Roll up cake in towel, jelly-roll style, starting with a short side. Cool completely on a wire rack.
3. For frosting, combine the sugar, cornstarch, salt and water in a saucepan until smooth. Bring to a boil; cook and stir for 2 minutes or until thickened. Remove from the heat. Add the chocolate, butter and vanilla; stir until melted.
4. While frosting is warm, unroll cake and spread half of frosting over cake to within 1/2 in. of edges. Roll up. Spread remaining frosting over outside of roll. Using tines of a fork, drag along sides of cake to resemble tree bark. Refrigerate for at least 1 hour before slicing.