Topping:
3/4 cup hot fudge, warmed
chopped pistachio nuts, optional
Recipe
Heat oven to 350 degrees Fahrenheit.
Lightly butter the bottom and sides of a 15 ½ x 10 ½-inch jelly roll pan. Line bottom of pan with parchment paper or aluminum foil.
Melt chocolate and butter in a medium bowl over a pan of simmering water, stirring until smooth. Remove from heat and cool slightly.
Meanwhile, place egg yolks in mixing bowl. Beat on medium-high until combined. Gradually add 3 tablespoons of the sugar and the vanilla. Beat 5 minutes or until yolks are pale yellow and mixture falls in thick ribbon when beater is lifted. Stir beaten egg yolks into chocolate mixture. Stir in flour.
Thoroughly wash bowl and beaters. Beat whites and cream of tartar until foamy. When soft peaks start forming, slowly add remaining sugar. Beat on high speed until whites almost hold stiff peaks.
Stir about 1/4 of the whites into chocolate mixture to lighten it. Fold in remaining whites. Pour batter into prepared pan and spread evenly. Bake until cake springs back when lightly touched, 10 to 12 minutes. Remove cake from oven and cool 5 minutes. Loosen edges of cake and invert onto a cloth dishtowel that has been sprinkled with confectioners’ sugar. Gently peel off paper. Roll cake and towel from long side into a loose roll. Let cool 15 minutes.
While cake is cooling prepare Mascarpone filling. Beat whipping cream and liqueur at high speed until soft peaks are formed. Slowly beat in sugar and beat until stiff. Add Mascarpone and beat slowly just until smooth. (Do not over beat.)
Gently unroll cake and spread with filling. Re-roll cake gently around filling. Trim off ends. (Sometimes the cake roll will develop cracks.) Cover and refrigerate at least one hour or overnight. To serve, cut into thin slices and drizzle each serving with some of the warmed ice cream topping. Sprinkle with chopped nuts.