Whisk the mascarpone cheese on medium speed for 30-60 seconds until creamy. Scrape the bowl and set aside.

In a separate heat-proof bowl, add the egg yolks and sugar. Boil 1-2" of water in a saucepan and reduce heat to the lowest setting. Place the bowl with egg yolks and sugar on top of the saucepan such that the water does not touch the bottom of the bowl. Whisk on medium-high speed for exactly 2 minutes, then remove from heat.

Pour the egg yolk and sugar mixture onto the mascarpone cheese. Add salt and vanilla, then whisk on medium speed just until combined.

In a separate bowl, whip the cold heavy cream until it reaches medium stiff peaks. Add the whipped cream to the mascarpone mixture in 2-3 additions, folding gently with a rubber spatula.

Pour the coffee into a wide bowl. Dip each ladyfinger quickly into the coffee and add a layer of soaked ladyfingers in the bottom of a 8x9.5" rectangular dish.

Spread on half of the mascarpone cream evenly.

Repeat with another layer of soaked ladyfingers.

Top with the remaining mascarpone cream.

Cover and refrigerate for at least 6 hours, or ideally overnight.

When ready to serve, sift the cocoa powder evenly on top of the tiramisu. Cut into slices and serve.