Ingredients
All-purpose flour, for work surface
1 3/4 pounds Puff Pastry dough
1/3 cup heavy cream
2 1/2 ounces dark semisweet chocolate, coarsely chopped (about 1/3 cup)
1/2 teaspoon corn syrup
1/4 ounce white chocolate, chopped (about 1 tablespoon)
Pastry Cream
Preparation
Make puff pastry strips: Lightly flour a clean work surface. Using a rolling pin, gently roll out dough into a 16-by-18-inch rectangle about 1/8 inch thick, being careful not to press too hard around the edges. Using a pastry wheel or sharp knife, cut rectangle crosswise into thirds, with each strip 6 by 16 inches. Transfer to a baking sheet; dock, or pierce, the dough all over with a fork. Cover with plastic wrap; place in refrigerator 1 hour.
Preheat oven to 425 degrees. Transfer to oven; bake until strips are puffed and golden all over, about 14 minutes. Set a baking sheet directly on pastry strips, and continue baking until pastry is cooked through and well browned, about 6 minutes. Remove top baking sheet; bake 4 minutes more. Transfer to a wire rack to cool completely. Using a serrated knife, trim each to 4 1/4 by 12 inches.
Make the glaze: In a small saucepan, bring heavy cream just to a boil. Place dark chocolate in a bowl, and pour hot cream over chocolate; whisk until chocolate is melted and mixture is combined. Whisk in corn syrup. Strain through a fine mesh sieve into a clean bowl.
Place white chocolate in a medium heat-proof bowl set over a pan of simmering water. Whisk until chocolate is melted, and remove from heat. Let cool.
Using an offset spatula, spread dark chocolate glaze over one side of the flattest puff pastry strip, making sure to coat entire surface. Place white chocolate in a piping cone; pipe thin lines 3/4 inch apart across width of chocolate-coated strip. To create the distinctive flourish, gently drag the tip of a paring knife or a skewer lengthwise through both coatings, in lines perpendicular to the white chocolate lines. Begin at one of the short ends, and make each line 3/4 inch apart. Alternate the direction each time.
Place one of the unglazed puff pastry strips on a serving tray. Spread half the pastry cream over the top, leaving a 1/2-inch border all around. Top with remaining unglazed pastry strip; press down gently, and repeat with remaining pastry cream. Top with glazed pastry strip. Transfer to refrigerator, and chill 30 minutes uncovered. Using a long serrated knife, cut into six pieces, and serve.
