How to Make It
Preheat oven to 400°F. Line 2 baking sheets with parchment paper, and set aside. Place thawed puff pastry sheets on a lightly floured surface, and roll each out to a 12-inch square. Cut each square into 9 (4-inch) squares. Place 4-inch squares on prepared baking sheets.
Whisk together egg and 1 tablespoon of the heavy cream in a small bowl. Lightly brush egg mixture on each square, and lightly sprinkle evenly with 1 tablespoon of the granulated sugar. Place baking sheets in preheated oven, and bake until squares are puffed and lightly golden brown, 10 to 11 minutes. Remove and cool slightly.
While puff pastry bakes, combine fruit, lemon juice, and 1 tablespoon of the sugar in a medium bowl, and toss to coat; set aside.
Combine marzipan, mascarpone cheese, vanilla extract, and 1/4 cup of the sugar in a food processor. Process until mixture is smooth, scraping down sides as needed.
Beat together remaining 1 1/2 cups heavy cream and 2 tablespoons sugar with an electric mixer on high speed until stiff peaks form, about 3 minutes. Gently fold mascarpone cheese mixture into whipped cream until combined. Stir in lemon zest; set aside.
Assemble the shortcakes: Place 1 puff pastry square on a plate, spoon 1/2 cup of the cream mixture onto square, top with about 1/2 cup of the fruit and juices, and top with another puff pastry square. Dust with powdered sugar.