Brew a cup of strong coffee and let it cool. If using, add the coffee liqueur to the cooled coffee and mix well.
In a mixing bowl, add the mascarpone cheese, heavy whipping cream, powdered sugar, and vanilla extract. Using an electric mixer, beat until the mixture is smooth and thickened.
Take the ladyfinger cookies and quickly dip each one into the coffee mixture for just a second to soak them.
In a trifle dish or individual serving glasses, layer the bottom with a third of the soaked ladyfingers.
Add a layer of mascarpone cream on top of the ladyfingers, smoothing it out evenly.
Sprinkle a layer of mixed fresh berries over the mascarpone cream, spreading them out evenly.
Repeat the layers two more times: ladyfingers, mascarpone cream, and berries, finishing with a layer of berries on top.
If desired, dust the top with unsweetened cocoa powder for added flavor and decoration.
Cover and refrigerate for at least 2 hours before serving to allow the flavors to meld.