Unfold the cold puff pastry sheet on a lightly floured surface.

Sprinkle the parmesan and cracked pepper evenly over the entire surface, pressing gently so it sticks.

Starting from one long edge, roll the pastry tightly toward the center, stopping exactly at the midpoint.

Roll the opposite edge toward the center in the same way, so the two rolls meet and touch in the middle.

Wrap the rolled log in plastic and chill in the freezer for 30 minutes, until firm enough to slice cleanly.

Preheat the oven to 375°F and line a baking sheet with parchment.

Slice the chilled log into 1/2-inch rounds and lay them flat on the baking sheet, spaced 2 inches apart.

Brush the tops lightly with egg wash and sprinkle with flaky salt.

Bake for 8 minutes, then flip each piece over with a spatula and bake for another 6 to 8 minutes, until both sides are deep golden and the pastry feels crisp, not soft, when tapped.

Cool on the sheet for 5 minutes before serving, since the caramelized sugar in the parmesan stays hot.