Preheat oven to 400°F. Line a baking sheet with silicon sheet or parchment paper.

Place the pastry on parchment paper or lightly floured cutting board. Using a sharp knife, divide the dough in half, rotate 90 degrees and half again, repeating until you have 16 squares. If you prefer you can make 8 squares for larger pastries.

Mix the egg and vanilla, adding a little water to thin.

Lightly brush the squares with the egg wash.

Place a square at the edge of a square and roll up, placing the seam side down. If you are using a thin chocolate bar you may want to stack 2 squares.

Place the roll on the prepared baking sheet and brush the tops with the remaining glaze.

Sprinkle with sugar (optional).

Bake the rolls until golden brown which should take 15 minutes.

Serve warm, or cool and drizzle with melted chocolate if you like.