Combine sugar, cornstarch, and salt in medium saucepan. Stir in milk until well blended; cook over medium heat, stirring constantly, until mixture boils (it will be quite thin). Add about 2 tablespoons milk mixture to eggs; beat well. Stir eggs into remaining milk mixture in saucepan. Cook, stirring constantly, until mixture starts to bubble. Stir in vanilla. Remove from heat, cover with waxed paper, and let cool. Place cake cubes in glass bowl. Sprinkle with 3 tablespoons brandy; drizzle with preserves. Pour cooled egg mixture over cake cubes. Place cream and confectioners' sugar in bowl; whip until stiff. Fold in 1 tablespoon brandy. Top trifle with whipped cream. Garnish with grated chocolate. Cover and refrigerate for several hours before serving.