In a saucepan, bring some water to a boil, then reduce the heat to a simmer. Have ready 2 mixing bowls that will fit over the top of the pan but not sink all the way in.
Put the egg yolks in one of the mixing bowls off heat. Add 1/4 cup of the sugar and whisk until the yolks start to turn pale. Place the mixing bowl over the saucepan with the simmering water. Slowly add 1/2 cup of the Marsala wine and whisk to combine. Cook over the simmering water until thick, using a rubber spatula to scrape the bowl, about 5 minutes. Cover with plastic wrap and refrigerate until cool.
Put the white chocolate in the second bowl and melt over the pan of water. Set aside to cool.
Put the mascarpone in a bowl and stir until smooth. Pour in the cooled white chocolate and mix to combine.
Combine the cream and remaining 1/4 cup sugar in a mixer and whip until not quite stiff. Add the mascarpone-white chocolate mixture and chilled egg yolk mixture to the bowl of whipped cream and fold gently. Cover with plastic wrap and refrigerate for 1 to 2 hours.
Put the brewed espresso, vanilla and remaining 1/4 cup Marsala in a bowl or measuring cup. Arrange about a third of the ladyfingers in a single layer in a 9-by-13-inch pan. Spoon a small amount of the coffee mixture over each ladyfinger (keep it under 1 tablespoon per cookie and you'll be fine). Plop one-third of the cold cream mixture on top and spread it into a layer. Make a layer of one-third of the halved strawberries and grate over some semisweet chocolate. Repeat the layers 2 more times.
Cover and refrigerate for a few hours before serving; this allows for more moisture to soften the cookies and the whole mixture to meld together. To serve, spoon out helpings onto individual plates. Top with Chocolate Curls.
Put the chocolate in a microwave-safe bowl with the vegetable shortening and microwave until melted and hot, 30 to 45 seconds. Stir to combine.
Pour the melted chocolate mixture onto the underside of a clean baking sheet and then spread it in a very thin layer with an offset spatula or knife. Put in the freezer for a few minutes.
After a few minutes, check to see if it is set by pressing with your fingertip; it should leave the slightest mark but not a depression. Using a sharp-edged spatula, begin to scrape the chocolate from the bottom of the baking sheet--it will curl. Transfer the curls to a cold pan or plate and put in the freezer to harden. Store in the freezer in a ziptop bag until needed.
Tiramisu does not last beyond 24 to 36 hours, as everything eventually starts to break down and become soupy.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.