Heat the oven to 350 degrees. Unfold puff pastry, and place on two baking sheets. Bake until the dough has puffed but is still soft and not yet browned, 7 to 10 minutes. Set a wire rack directly on top of the dough, and press gently to flatten to about 1/8 inch. Bake until lightly browned, 8 to 10 minutes. Cool on a wire rack.
Transfer pastry to a cutting board. Increase the oven temperature to 475 degrees. Using a serrated knife, cut the pastry into eighteen 2- by 3-inch rectangles. (If you have extra pastry, cut out a few more rectangles to replace any that break.) Evenly dust the pastry with 1/2 cup confectioners' sugar. Return to the baking sheet and bake until the sugar is melted to a glaze, and the pastry is browned, 2 to 3 minutes. Transfer to a rack, and let cool. (This can also be done under a broiler, watched very closely.)
In a medium bowl, mash the berries with a fork. Stir in the sugar, using just enough to take the edge off the tartness. Let them macerate for 20 to 30 minutes to bring out the juices. Transfer to a blender or food processor and puree until smooth. Strain through a fine mesh sieve to remove the seeds, reserving the coulis. Adjust thickness if necessary with a little water. (
Makes about 1/2 cup)
To assemble the Napoleons, transfer the whipped cream into a disposable pastry bag. Cut off about 1/2-inch of the tip of bag with scissors. Pipe 1/4-inch-thick layer of whipped cream over twelve of the pastry rectangles. Top with a single layer of berries. Stack six of the filled pastries on top of the other. Top with the plain pastry. Place each on a dessert plate and drizzle about 2 tablespoons of raspberry coulis around the pastry.