Prepare the coffee: Brew 3 cups of strong coffee and allow it to cool to room temperature. Stir in 2 tablespoons of coffee liqueur if desired.
Make the custard: In a large bowl, whisk the 4 egg yolks and 1/2 cup of granulated sugar together until the mixture becomes pale and creamy, about 5 minutes.
Add the mascarpone: Gently fold in the 8 ounces of mascarpone cheese until well combined and smooth.
Whip the egg whites: In a separate bowl, whip the 4 egg whites until soft peaks form. Carefully fold these into the mascarpone mixture, being cautious not to deflate it.
Whip the cream: In another bowl, whip the 1 cup of heavy cream until stiff peaks form. Gently fold this into the mixture as well, creating a light, airy texture.
Assemble the layers: Dip each ladyfinger briefly into the cooled coffee, ensuring they are softened but not soggy. Place a layer of dipped ladyfingers at the bottom of your serving dish.
Layer the filling: Spread half of the mascarpone mixture over the layer of ladyfingers. If using, drizzle 1/2 cup of chocolate ganache over this layer for added decadence.
Add another layer: Repeat the process with another layer of dipped ladyfingers and the remaining mascarpone mixture.
Chill the dessert: Cover the dish and refrigerate for at least 4 hours or preferably overnight to allow the flavors to meld and the tiramisu to set.
Final touch: Before serving, dust the top with 2 tablespoons of unsweetened cocoa powder. You can also add chocolate shavings or a dollop of whipped cream for garnish.