Peel away the parchment from sponge cake. Cut cake into 3 equal pieces and place 1 piece on a decorative platter or board for serving.
Make the chocolate ganache: Place the chocolate in a heat-proof bowl. In a small saucepan, scald 1 cup of cream over medium heat. Pour over the chocolate and let sit for 2 minutes, then whisk until smooth. Let cool slightly before pouring on the cake.
Spread half of the chilled pastry cream over the bottom cake layer, spreading evenly with an offset spatula almost all the way to the edges. Place another cake layer on top and cover with the remaining pastry cream. Place the last cake layer on top and starting in the middle, slowly pour half of the chocolate over the cake and out to the sides. Let sit for 5 minutes, then in several applications, pour the rest of the chocolate over the cake to completely cover. Chill until set up and ready to serve, about 2 hours.
In a large bowl, using an electric mixer on medium speed, beat 1 1/3 cups cream until frothy. Add the sugar and vanilla and beat until the cream holds soft peaks.
Spoon the whipped cream over the top of the cake as desired. Garnish the top with chocolate shavings and serve immediately.
In a large heavy saucepan, combine the milk and vanilla bean pods and seeds. Bring to a gentle boil over medium heat. Remove from the heat.
In a large bowl, beat together the egg yolks and sugar until thick and pale yellow, about 4 minutes. Mix in the cornstarch. Slowly add about 2 cups of the hot milk mixture to the egg yolks, whisking until smooth. Add the egg yolk mixture to the pot of hot milk and whisk to combine. Return to medium heat and cook, stirring constantly with a heavy wooden spoon until the mixture is very thick, about 5 minutes.
Remove from the heat and strain into a clean container. Discard the vanilla bean pods or rinse and reserve for another use. Cover with plastic wrap, pressing down against the surface to prevent a skin from forming. Refrigerate until well chilled, at least 6 hours, before using.
Yield: about 7 cups
Preheat the oven to 350 degrees F. Lightly grease 2 large sheet pans and line with parchment paper. Grease the parchment paper and set aside.
In the bowl of an electric mixer, combine the egg yolks, 1 cup of the sugar, and the vanilla, and beat until thick, about 5 minutes. In a clean bowl with an electric mixer, whip the whites and salt until thick and foamy. With the machine on high speed, beat in the remaining sugar gradually, and continue to whip until stiff peaks form. Fold into the yolk mixture.
In several additions, sift together the cornstarch and flour into the yolk mixture, folding gently to incorporate. Evenly spread mixture onto prepared sheets. Bake until golden brown and starting to pull away from the sides of the pan, 10 to 15 minutes.
Cool on the sheet and use as directed for making the cake.
Yield: 1 large sheet pan of sponge cake