Ice Cream Cake Roll

INGREDIENTS
4 eggs, separated
3/4 cup sugar
1 teaspoon vanilla extract
3/4 cup cake flour
1/4 cup baking cocoa
3/4 teaspoon baking powder
1/4 teaspoon salt
3 cups ice cream, softened
CHOCOLATE SAUCE:
2 (1 ounce) squares unsweetened baking chocolate
1/4 cup butter
2/3 cup evaporated milk, heated to 160 degrees F
1 cup sugar
DIRECTIONS
Let eggs stand at room temperature for 30 minutes. Line a greased 15-in. x 10-in. x 1-in. baking pan with waxed paper; grease and flour paper; set aside.
In a large mixing bowl, beat egg yolks on high for 3 minutes or until lemon-colored. Gradually add sugar and vanilla, beating until thick and pale yellow. Combine the flour, cocoa and baking powder; gradually add to egg yolk mixture Beat on low until well mixed (mixture will be thick).
In another large mixing bowl and with clean beaters, beat egg whites and salt on high speed until soft peaks form. Fold a fourth of egg whites into the batter, then fold in remaining whites.
Spread batter evenly in prepared pan. Bake at 350 degrees F for 15 minutes or until cake springs back when lightly touched. Turn cake onto a kitchen towel dusted with confectioners' sugar. Gently peel off waxed paper. Roll up cake in the towel jelly-roll style, starting with a short side. Cool completely on a wire rack.
Unroll cake; spread with ice cream to within 1 in. of edges. Roll up again. Cover with plastic wrap and freeze until serving.
In a small heavy saucepan, melt chocolate and butter over low heat, stirring until smooth. Gradually add warm milk and sugar; stir constantly for 5 minutes or until completely dissolved. Serve with cake.