01 - Set the oven temperature to 400°F and line a baking sheet with parchment paper.
02 - On a lightly floured surface, roll out the puff pastry into a rectangle measuring approximately 12 × 10 inches.
03 - Divide the dough into 8 equal rectangles.
04 - Place about 0.4 oz of chopped chocolate along the short edge of each rectangle, then roll up tightly sealing the seam beneath.
05 - Position the pastries seam-side down on the parchment-lined sheet, spacing each apart.
06 - Brush the tops of the pastries evenly with the beaten egg to ensure a golden finish.
07 - Sprinkle sliced almonds on top if desired.
08 - Bake for 18 to 20 minutes, or until the pastries puff up and develop a golden-brown color.
09 - Allow the pastries to cool slightly on a wire rack. Dust with powdered sugar before serving, if wished.