Start the cream. In a medium saucepan, combine the eggs and sugar. Mix with a hand mixer until well combined and pale.
Add the starch and flour. Add the cornstarch and flour, adding the flour in doses and checking the cream as you go. Mix again until smooth.
Heat the milk. In a small saucepan, warm the milk with the vanilla until very hot but not boiling.
Combine. Slowly pour the hot milk over the egg mixture while stirring constantly, so the eggs do not scramble.
Cook the cream and cool. Place the pan on the stove and stir continuously with a whisk. When the cream thickens and begins to bubble, with big air bubbles popping on the surface, turn off the heat immediately. Set the cream aside to cool completely, covered.
Make the light coffee. Bring the water and ground coffee to a boil, and stop as soon as it starts to boil. This gives a very light coffee with a gentle flavor that is mild enough for kids. Let it cool.
Finish the cream. Once everything is cool, mix the cooled cream with the mixer. Then add the cold mascarpone gradually, mixing until perfectly smooth and uniform.
Start layering. Spread a thin layer of cream on the bottom of your dish. This is optional, but it helps the biscuits sit nicely.
Dip and arrange. Dip each ladyfinger quickly in the coffee, one by one, and arrange them in a single layer in the dish.
Add cream. Cover with a layer of cream. Divide the cream carefully so you have enough for every layer. Three layers work best.
Repeat. Continue with the next 2 layers, finishing with a layer of cream on top.
Dust. Sprinkle the top generously with unsweetened cocoa powder.
Rest. Leave at room temperature for 1 hour, then refrigerate for at least 6 hours. Overnight is better, and it tastes best after 24 hours.
Decorate. Finish with berries, shaved chocolate, or simply with more cocoa.
