First Step: Macerate the Berries
Combine fresh raspberries, blackberries, and blueberries in a large bowl. Add approximately half of the granulated sugar (about ¼ cup), 1 teaspoon vanilla extract, and juice of half a lemon. Let the berries macerate for 15 to 30 minutes up to 2 hours for deeper flavor release to allow juice to develop.

Second Step: Prepare Mascarpone Cream
Drain the excess berry juice into a separate container and pat the berries dry on paper towels to prevent over-moistening the dessert. Beat mascarpone cheese until smooth in a large bowl. Gradually add about ¼ cup heavy cream to loosen it before adding the rest of the heavy cream. Whip at high speed until soft peaks form. Add powdered sugar and the remaining teaspoon of vanilla extract, then whip to stiff peaks for a fluffy texture.

Third Step: Soak the Ladyfingers
Mix the reserved berry juice with milk. Add optional liquor such as rum, brandy, or raspberry liqueur to this soaking liquid if desired. Quickly dip ladyfingers individually into this mixture without over-soaking to maintain structure, then arrange a layer of soaked ladyfingers in the bottom of a 9-inch square or 8×8 inch dish.

Fourth Step: Assemble Layers
Spread half of the mascarpone cream evenly over the ladyfingers layer. Gently arrange half of the dried macerated berries on top of the cream, pressing lightly to incorporate. Repeat the layering sequence with remaining ladyfingers, mascarpone cream, and berries, ending with a final layer of mascarpone cream.

Final Step: Chill and Garnish
Cover the tiramisu and refrigerate for at least 2 to 4 hours or preferably overnight to allow flavors to meld and for easier slicing. Before serving, dust the top with powdered freeze-dried strawberries or a mix of freeze-dried berry powders to add color and a burst of extra berry flavor. Serve chilled for a refreshing dessert experience.