Creating a tiramisu cake involves several steps, but with careful attention, you can achieve restaurant-quality results. Follow these instructions:

Step 1: Prepare the Coffee Mixture

1. Brew 300 ml of strong espresso or coffee and allow it to cool to room temperature.
2. Stir in the coffee liqueur if using, and set aside.

Step 2: Make the Mascarpone Cream

1. In a large mixing bowl, whisk the egg yolks and sugar together until the mixture is pale and thick.
2. Add the mascarpone cheese and vanilla extract to the egg mixture, gently folding until smooth and well combined.
3. In a separate bowl, whip the heavy cream until stiff peaks form.
4. Carefully fold the whipped cream into the mascarpone mixture, ensuring it’s evenly mixed without deflating the cream.

Step 3: Assemble the Tiramisu

1. Quickly dip each ladyfinger cookie into the coffee mixture, ensuring they are soaked but not soggy.
2. Arrange a single layer of soaked ladyfingers at the bottom of a rectangular dish.
3. Spread half of the mascarpone cream over the ladyfingers, smoothing it into an even layer.
4. Repeat the process with another layer of coffee-soaked ladyfingers, followed by the remaining mascarpone cream.
5. Cover the dish with plastic wrap and refrigerate for at least 4 hours or overnight for the best results.

Step 4: Serve and Garnish

1. Just before serving, dust the top of the tiramisu with a generous layer of unsweetened cocoa powder.
2. Garnish with dark chocolate shavings if desired.
3. Slice into portions and serve chilled.