For the zabaglione:.
Heat water in a double boiler. If you donu2019t have a double boiler, place a pot with about an inch of water in it on the stove.
Place a heat-proof bowl in the pot making sure the bottom does not touch the water.
In a large mixing bowl (or stainless steel mixing bowl), mix together the egg yolks, sugar, the Marsala (or espresso/ coffee), vanilla extract and lemon zest. Whisk together until the yolks are fully blended and the mixture looks smooth.
Transfer the mixture to the top of a double boiler or place your bowl over the pan/ pot with simmering water.
Cook the egg mixture over low heat, stirring constantly, for about 8 minutes or until it resembles thick custard. It may bubble a bit as it reaches that consistency.
Let cool to room temperature and transfer the zabaglione to a bowl.
Cover and refrigerate at least 4 hours or overnight, until thoroughly chilled.
For the vanilla pastry cream:.
Mix together the sugar, flour, lemon zest and vanilla extract in a medium heavy-bottomed saucepan.
To this add the egg yolk and half the milk. Whisk until smooth.
Now place the saucepan over low heat and cook, stirring constantly to prevent the mixture from curdling.
Add the remaining milk a little at a time, still stirring constantly.
After about 12 minutes the mixture will be thick, free of lumps and beginning to bubble (If you have a few lumps, donu2019t worry. You can push the cream through a fine-mesh strainer).
Transfer the pastry cream to a bowl and cool to room temperature.
Cover with plastic film and refrigerate at least 4 hours or overnight, until thoroughly chilled.
For the whipped cream:.
Combine the cream, sugar and vanilla extract in a mixing bowl. Beat with an electric hand mixer or immersion blender until the mixture holds stiff peaks. Set aside.
For Ladyfingers/ Savoiardi Biscuits: .
Preheat your oven to 350 F (175 C) degrees, then lightly brush 2 baking sheets with oil or softened butter and line with parchment paper. .
Beat the egg whites using a hand held electric mixer until stiff peaks form.
Gradually add granulate sugar and continue beating until the egg whites become stiff again, glossy and smooth.
In a small bowl, beat the egg yolks lightly with a fork and fold them into the meringue, using a wooden spoon.
Sift the flour over this mixture and fold gently until just mixed. It is important to fold very gently and not overdo the folding. Otherwise the batter would deflate and lose volume resulting in ladyfingers which are flat and not spongy.
Fit a pastry bag with a plain tip (or just snip the end off; you could also use a Ziploc bag) and fill with the batter.
Pipe the batter into 5" long and 3/4" wide strips leaving about 1" space in between the strips.
Sprinkle half the confectioner's sugar over the ladyfingers and wait for 5 minutes.
The sugar will pearl or look wet and glisten. Now sprinkle the remaining sugar. This helps to give the ladyfingers their characteristic crispness.
Hold the parchment paper in place with your thumb and lift one side of the baking sheet and gently tap it on the work surface to remove excess sprinkled sugar.
Bake the ladyfingers for 10 minutes, then rotate the sheets and bake for another 5 minutes or so until the puff up, turn lightly golden brown and are still soft.
Allow them to cool slightly on the sheets for about 5 minutes and then remove the ladyfingers from the baking sheet with a metal spatula while still hot, and cool on a rack.
Store them in an airtight container till required. They should keep for 2 to 3 weeks.
To assemble the tiramisu:.
Have ready a rectangular serving dish (about 8" by 8" should do) or one of your choice.
Mix together the warm espresso, rum extract and sugar in a shallow dish, whisking to mix well. Set aside to cool.
In a large bowl, beat the mascarpone cheese with a spoon to break down the lumps and make it smooth. This will make it easier to fold.
Add the prepared and chilled zabaglione and pastry cream, blending until just combined. Gently fold in the whipped cream. Set this cream mixture aside.
Working quickly, dip 12 of the ladyfingers in the sweetened espresso, about 1 second per side. They should be moist but not soggy.
Immediately transfer each ladyfinger to the platter, placing them side by side in a single row. You may break a lady finger into two, if necessary, to ensure the base of your dish is completely covered.
Spoon one-third of the cream mixture on top of the ladyfingers, then use a rubber spatula or spreading knife to cover the top evenly, all the way to the edges.
Repeat to create 2 more layers, using 12 ladyfingers and the cream mixture for each layer.
Clean any spilled cream mixture; cover carefully with plastic wrap and refrigerate the tiramisu overnight.
To serve, carefully remove the
plastic wrap and sprinkle the tiramisu with cocoa powder using a fine-mesh strainer or decorate as you please.
Cut into individual portions and serve.