• In a heatproof bowl, over a double boiler (a bowl set over simmering water), whisk the egg yolks, vanilla extract, and granulated sugar together until the mixture becomes pale and slightly thickened for about 4-5 minutes.
• Be careful not to overheat the egg mixture, as we’re just looking to gently warm it. You will know it is ready when you can’t feel sugar granules while rubbing a small amount between your fingers.
• When its ready, set it aside to cool completely.
• In a large mixing bowl, add the heavy cream and mix with an electric hand mixer until stiff peaks form.
• Add the room temperature mascarpone cheese and mix it until the mascarpone cheese is incorporated into the cream. Do not overmix since it can curdle.
• On low speed, gradually add the egg yolk mixture, mixing constantly until smooth, creamy, and homogeneous.

Assembly

• Dip the ladyfingers quickly in the coffee mixture (1-2 seconds) and lay them in an even layer in the 13 by 9-inch baking dish.
• Top the soaked ladyfingers with half of the mascarpone mixture and smooth it out with a spatula. Add another layer of the dipped ladyfingers.
• Top the ladyfingers with the other half of the mascarpone cream. Cover with plastic wrap and place in the fridge for at least 4 hours to allow the ladyfingers to soften.

Make the Chantilly cream (optional)

• Pour the cold heavy cream into the chilled bowl, then add the powdered sugar and vanilla.
• Using a hand mixer or stand mixer, beat on medium-high speed until soft peaks form (the cream holds its shape but still looks soft and smooth).
• Stop once you reach soft to medium peaks. Overwhipping can make the cream grainy or turn it into butter.
• Transfer the Chantilly cream into a piping bag with a round tip and make dollops of the cream all over the tiramisu. Generously top the tiramisu with plenty of cocoa powder and serve!