In a large saucepan, combine the milk with the vanilla and ¾ sugar. Bring to simmer, stirring to dissolve the sugar. Remove the heat, cover and let stand at room temperature for 1 hour. In a large bowl, whisk the egg yolks with the cornstarch and the remaining 1 cup of sugar. Whisk in 1 cup of the milk mixture. Whisk the egg mixture into the milk in the saucepan and cook over moderate heat, stirring constantly with a rubber spatula, until the custard just begins to thicken. Switch back to a whisk and cook for 4 minutes. Transfer the custard to a large heat proof bowl. Let cool, then press a sheet of plastic wrap directly onto the surface. Refrigerate for 3 hours. Preheat the oven to 170`c. Butter a 12 by 17 inch rimmed baking sheet and line the sheet with baking paper. Butter the baking paper and dust it with flour. In a bowl beat together the eggs, sugar and orange for 7 minutes. In a small bowl, whisk the flour with the corn starch and salt. Sift the flour mixture over the beaten eggs and fold it in. Pour the cake batter onto the prepared baking sheet and smooth the surface with a spatula. Bake in the oven for 20 minutes and let cool. In a small saucepan, combine the Marsala with the sugar and bring to simmer, stirring to dissolve the sugar. Run the blade of a paring knife along the sides of the cake and invert the cake onto a work surface. Peel the baking paper. Cut the cake into 3 inch squares. Reserve any scraps to patch holes. In a large glass trifle bowl, arrange a layer of cake squares. Using a pastry brush, soak the cake with some of the Marsala syrup. Top with a 1 inch layer of pastry cream. Repeat the remaining cake, syrup and pastry cream, ending with a layer of cake and syrup. Cover the trifle and refrigerate for at least 3 hours.