Position rack in center of oven. Heat oven to 375ºF. Line bottom of 15 ½-inch x 10 ½-inch baking sheet with parchment paper, leaving 2-inch overhang on short ends of pan. Lightly spray parchment paper and pan sides with cooking spray. Lightly dust parchment and sides of pan with cake flour and tap out excess flour.
Place chopped chocolate in microwavable bowls. Microwave chocolate on HIGH for 1 minute. Let stand for 30 seconds. Stir until melted and smooth. Set aside.
Beat egg yolks, 1/4 cup sugar and vanilla at medium-high speed about 5 minutes in medium bowl using electric mixer, or until batter forms a thick light yellow ribbon when beaters are lifted. Using a clean, dry rubber spatula, gently fold egg yolk mixture into chocolate mixture. Gently fold in 1 cup sifted flour.
Beat egg whites at medium-low speed in grease-free bowl of electric mixer until frothy. Increase speed to high and while beating, gradually add remaining 2 tablespoons granulated sugar, beating until whites form until stiff peaks form. Using clean, dry rubber spatula, fold one-third egg whites into the egg yolk/chocolate mixture to lighten. Gently fold in remaining egg whites.
Scrape batter into prepared pan and gently smooth surface with an offset spatula. Bake sponge cake for 20 minutes, or until cake tester inserted in center comes out clean. While cake is baking, place a 15 ½-inch x 10 ½-inch piece of parchment paper on work surface and dust with confectioners’ sugar.
Run a thin-bladed knife around edges of cake to loosen it from sides of pan and immediately invert it onto sugar-coated parchment paper; remove pan. Starting at the long end, roll cake up loosely with parchment paper into a jelly-roll. Cool completely.
Place softened ice cream into a medium bowl and mix with a wooden spoon until just spreadable. Carefully unroll cake (be careful not to crack cake). Place brandy in a small bowl and liberally brush entire cake, especially the edges. Using an offset spatula, gently spread ice cream into an even layer. Using parchment paper as a guide, re-roll cake into a tight cylinder. Wrap cake roll tightly in a piece of plastic wrap, and twist ends to secure. Freeze roll for at least 1 hour or until ready to glaze.
Combine cream, corn syrup and butter in medium saucepan over medium heat. Heat to a boil. Remove from heat and add chopped chocolate. Let stand 1 minute. Stir until melted and smooth. Cool the glaze to about 86ºF. or until it starts to thicken slightly.
Remove the cake roll from the freezer and remove the plastic wrap. Place cake roll on a wire rack set over a waxed paper-lined baking sheet. Slowly pour glaze evenly down center of cake roll, allowing glaze to cover cake roll completely. Return to freezer.
Make Crème Anglaise:
Place milk, cream and split vanilla bean in a medium saucepot. Heat to a boil over medium-high heat. Reduce heat to low. Cover and heat milk mixture with vanilla bean for about 20 minutes. Remove vanilla bean. Reheat mixture to boiling.
Place egg yolks and sugar in medium bowl and beat until thick and light, using a wire whisk. Whisk half hot milk mixture into egg yolks until blended. Whisk mixture back into remaining hot milk mixture. Heat gently, stirring constantly with wooden spoon, until custard thickens slightly. Custard is ready when a clear trail is left behind when you draw your finger across the back of the spoon. Do not overheat or mixture will curdle.
Remove custard from heat at once and strain through fine mesh strainer into a bowl. Let cool completely; cover tightly and chill. Custard will keep for up to 3 days in refrigerator.
Place a spoonful of crème anglaise on each of 6 small dessert plates. Top with cake slice and garnish with toasted pistachios.