01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper.
02 - On a lightly floured surface, roll out the puff pastry to a rectangle measuring approximately 12 × 10 inches.
03 - Cut the pastry into 8 equal rectangles.
04 - Place about 0.4 oz of dark chocolate along the short edge of each rectangle. Roll tightly, sealing the seam underneath.
05 - Place pastries seam-side down on the prepared baking sheet, spacing them evenly apart.
06 - Brush each pastry with beaten egg for a golden finish. If desired, sprinkle sliced almonds on top.
07 - Bake for 18 to 20 minutes, or until pastries are puffed and golden brown.
08 - Allow pastries to cool slightly on a wire rack. Dust with powdered sugar before serving, if preferred.