For the poached pears:
In a medium saucepan, bring the water, honey, seeds from the vanilla bean and vanilla bean to a boil until the honey dissolves. Add the pear halves, reduce the heat, cover and simmer until the pears are tender when pierced with a sharp knife, about 12 - 15 minutes. Transfer the pears with a slotted spoon to a cutting board and cut into thin slices.
For the Crème Anglaise:
In a small saucepan, bring the cream to a bare boil with the vanilla bean and seeds over medium heat. Cool slightly.
In a medium saucepan, blend the egg yolks and sugar with a whisk until it forms ribbons. Gradually add the warm cream, and mix well, stirring constantly over medium heat. Strain through a fine mesh strainer and keep warm, covered, until ready to use.
Assemble the Trifle:
Trim the crust from the cake and cut the cake into 1/2-inch thick slices to fit tightly into the bottom of a trifle bowl (or alternately, a 1 1/2-quart decorative glass bowl), and slightly up the sides about 1-inch. Drizzle the cake with some of the Port.
In a mixing bowl toss the berries with 2 tablespoons Port, stirring to bruise the berries slightly. In a medium bowl, whip the cream with the sugar.
Layer one-third of the pears over the top of the cake, then top with one-third of the Crème Anglaise, followed by one-third of the raspberries. Repeat the process with the remaining cake, Port, pears, custard, raspberries for two layers each, finishing with the whipped cream on top. Decorate the top with chocolate shavings.
Yield: 1 large trifle, approximately 12 servings