Step 1For the prune filling: In a medium saucepan, combine the prunes with one-fourth cup sugar and 1 1/4 cups water. Bring to a simmer over medium-high heat. Reduce the heat to a gentle simmer and cook for 10 minutes. Remove from the heat and allow the prunes to cool in the liquid. Add the almond extract. Puree the mixture in a food processor or blender, or using an immersion blender. Set aside.
Step 2For the mascarpone cream: In the bowl of a stand mixer or in a medium bowl with a hand mixer, whip the mascarpone with the heavy cream just until the mixture begins to hold its shape. Add the remaining one-third cup sugar and whip until soft and creamy, but not stiff, about 2 minutes. Set aside.
Step 3In a small bowl, mix together the espresso, amaretto and brandy, then set aside.
Step 4Spread one-third of the mascarpone cream in the bottom of a 2-quart rectangular baking dish. Sprinkle one-third of the grated chocolate evenly over the cream.
Step 5Dunk each ladyfinger in the espresso mixture, making sure they're submerged long enough to be thoroughly saturated. (Tear into one to make sure.) Create the first layer of the well-soaked ladyfingers, placing them snugly against one another.
Step 6Spoon the prune filling over the ladyfingers and spread evenly.
Step 7Spread half of the remaining mascarpone cream over the prune filling and sprinkle with half of the remaining ground chocolate.
Step 8Make another layer of ladyfingers, following the instructions in Step 5. If you run low on the espresso mixture, add more espresso to soak the ladyfingers.
Step 9Cover the ladyfingers with the remaining mascarpone cream, then lightly sprinkle evenly with the remaining ground chocolate. Cover with plastic wrap and refrigerate for at least 8 hours or overnight before serving.