BANANA-CARAMEL NAPOLEONS

Steps:

• Combine 1 cup sugar, 6 tablespoons water and lemon juice in heavy small saucepan. Stir over low heat until sugar dissolves. Increase heat and boil without stirring until syrup turns deep amber, brushing down sides of pan with wet pastry brush and swirling occasionally, about 10 minutes. Remove from heat. Carefully add cream (mixture will bubble vigorously). Stir until mixture is smooth. Transfer caramel to small bowl. Cover and refrigerate until thick, about 3 hours.
• Preheat oven to 400°F. Line 2 heavy large baking sheets with parchment paper, roll out pastry on lightly floured surface to 15x12-inch rectangle. Cut crosswise into three 12x5-inch strips. Transfer pastry strips to prepared baking sheets, spacing evenly. Chill 10 minutes.
• Pierce pastry with fork. Bake until golden, about 15 minutes. Transfer baking sheets to racks; cool. (Caramel and pastry can be made 2 days ahead. Keep caramel refrigerated. Wrap pastry in foil; store at room temperature.)
• Set aside 1/2 cup caramel for decoration. Using electric mixer, beat mascarpone and 1 1/2 tablespoons sugar in medium bowl until smooth. Add remaining caramel and beat until caramel cream is well blended, about 1 minute.
• Trim pastry layers so that they are flat and even. Place 1 pastry strip on work surface. Spread with 1/4 of caramel cream. Arrange half of banana slices in single layer over caramel cream. Spread second pastry strip with 1/4 of caramel cream; place pastry, caramel cream side down, atop bananas. Spread top of second pastry strip with 1/4 of caramel cream. Arrange remaining bananas in single layer over. Spread remaining pastry strip with remaining caramel cream. Place pastry, caramel cream side down, atop bananas. Using serrated knife, cut pastry crosswise into 8 equal pieces. Sift powdered sugar over. (Can be made 2 hours ahead. Tent with foil; refrigerate.)
• Place napoleons on plates. Drizzle reserved caramel around napoleons.