This dessert, a favorite of chef Eberhard Mueller, is a twist on the classic Napoleon and uses Alpine strawberries between layers of crisp puff pastry and freshly whipped cream.
Preheat 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 the pastry 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 mixing bowl, combine heavy cream and creme fraiche. Add vanilla seed scrapings and the remaining 2 tablespoons confectioners' sugar; whisk until stiff.
To assemble the Napoleons, transfer the whipped cream into a disposable pastry bag. Cut off about 1/2 inch of the tip of the bag with scissors. Pipe a 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 six. Top each stack with a plain pastry. Place each Napolean on a dessert plate, and drizzle about 2 tablespoons raspberry coulis around the pastry.