Mascarpone Cream Option 1: Using Heavy Cream (Recommended)

Whisk the mascarpone cheese on medium speed for 30 to 60 seconds until smooth and creamy. Scrape down the bowl and set aside. In a separate heatproof bowl, combine the egg yolks and ⅔ cup sugar. Bring 1 to 2 inches of water to a boil in a saucepan, then reduce the heat to the lowest setting. Place the bowl with the egg yolks and sugar over the saucepan, ensuring the water does not touch the bottom of the bowl—this creates a double boiler. Whisk the mixture on medium-high speed for exactly 2 minutes, then remove from heat. The mixture should become light and fluffy; avoid overmixing or overheating as this can cause graininess.* Pour the egg yolk and sugar mixture over the mascarpone cheese. Add salt and vanilla, then whisk on medium speed just until combined, scraping the bowl halfway down. Do not overmix to prevent graininess. In a separate bowl, whip the cold heavy cream until it reaches medium stiff peaks (just beginning to hold shape). Avoid overwhipping. Gently fold the whipped cream into the mascarpone mixture in 2 to 3 additions using a rubber spatula, taking care not to deflate the air. This will create a creamy, light texture.

Mascarpone Cream Option 2: Using Egg Whites

Whisk the mascarpone cheese on medium speed for 30 to 60 seconds until creamy. Scrape down the bowl and set aside. In a separate heatproof bowl, combine the egg yolks and ⅓ cup sugar. Prepare a double boiler as above, whisking on medium-high speed for exactly 2 minutes until the mixture is light and fluffy. Remove from heat, being careful not to overmix or overheat.* Pour this mixture over the mascarpone cheese. Add salt and vanilla, then whisk on medium speed until just combined, scraping down the bowl halfway. In a clean bowl, add the egg whites and the remaining ⅓ cup sugar. Place this bowl over the simmering water again, whisking on medium-high speed until the mixture reaches 160°F (5 to 8 minutes). Remove from heat and continue whisking until a glossy, stiff meringue forms.* Fold the meringue gently into the mascarpone mixture in 2 to 3 additions with a rubber spatula, being careful to maintain the airy texture.

Assembly and Serving:

Pour the room temperature coffee into a wide bowl. Quickly dip each ladyfinger into the coffee, doing a quick dip on each side,* then arrange a layer of soaked ladyfingers in the bottom of an 8 x 9.5-inch rectangular dish.* Spread half of the mascarpone cream evenly over the ladyfingers. Repeat the process with another layer of dipped ladyfingers. Top with the remaining mascarpone cream. Cover and refrigerate for at least 6 hours, preferably overnight. Before serving, sift cocoa powder evenly over the tiramisu. Slice and serve immediately!