Panettone Tiramisù

Make the pastry cream: Place the milk in a medium saucepan and set over medium heat. Split open the vanilla bean lengthwise and scrape the seeds into the milk. Toss in the pod and heat the milk just until it begins to boil. Remove from the heat, and remove and discard the vanilla bean.

Combine the egg yolks and 2/3 cup sugar in a bowl and whisk together until pale yellow. Whisk in the flour. Dribble a little of the hot milk into the egg mixture, whisking as you go to prevent the eggs from cooking. Continue to slowly whisk milk into the eggs until you have added about half the milk. Slowly pour this mixture back into the remaining hot milk, stirring as you pour. Return the pot to medium heat and cook, stirring continuously with a whisk or spatula, until it has thickened and is just about to boil. Immediately turn the heat to low and continue to cook for 3 to 4 minutes, stirring continuously to avoid scorching.

Remove the pastry cream from the heat and pour it into a bowl. Cover the top with plastic wrap, pressing the wrap right onto the surface of the cream. Let the pastry cream come to room temperature and then refrigerate until thoroughly chilled.

Whip 1 cup heavy cream with 8 ounces mascarpone and 2 tablespoons sugar until stiff. Gently fold the whipped cream and mascarpone into the chilled pastry cream. Cover with plastic wrap and refrigerate until ready to use.

Assemble the tiramisu: Cut the Panettone into 3/4-inch-thick slices (either lengthwise or crosswise). Arrange some of the slices in the bottom of a 13-inch by 9-inch baking dish (I use a lasagne dish). Press the slices together so that they fit snugly in one layer. (You can tear the slices and fill gaps with small pieces of cake.)

Mix together the espresso and Grand Marnier. Using a pastry brush, brush half the espresso mixture over the Panettone slices in the baking dish. Sprinkle half the chopped bittersweet chocolate on top. Spread half the pastry cream-mascarpone mixture evenly over the Panettone slices. Arrange a second layer of Panettone slices over the pastry cream mixture and brush with the remaining spiked espresso. Sprinkle the remaining chopped chocolate over the slices and spread the rest of the pastry cream mixture evenly over the top. Cover tightly with plastic wrap and refrigerate.

Whip the remaining 1 cup heavy cream, 8 ounces mascarpone and 2 tablespoons sugar until stiff. Spread the whipped cream-mascarpone mixture over the top of the tiramisu. Cover tightly with plastic wrap and refrigerate for at least 8 hours and preferably overnight. Dust liberally with cocoa powder (or sprinkle with more shaved chocolate) right before serving. Serve chilled.