In a bowl, whisk together the mascarpone cheese, granulated sugar, egg yolks, and vanilla extract until smooth and creamy. Use an electric mixer if needed.
In a separate chilled bowl, whip the heavy cream until stiff peaks form.
Gently fold the whipped cream into the mascarpone mixture until just combined.
Quickly dip each ladyfinger into the cooled coffee mixture, ensuring not to soak them too long.
Arrange a single layer of coffee-dipped ladyfingers in the bottom of a 9-inch springform pan or a similar-sized serving dish.
Spread half of the mascarpone cream mixture evenly over the ladyfinger layer.
Repeat the layers with dipping the remaining ladyfingers in coffee and arranging them on top of the cream mixture.
Spread the remaining mascarpone cream mixture over the second layer of ladyfingers, smoothing the top.
Cover the cake tightly with plastic wrap.
Refrigerate for at least 4 hours, or preferably overnight, to allow the flavors to meld and the cake to set.
Before serving, carefully dust the top of the Tiramisu cake generously with unsweetened cocoa powder.