Heat oven to 400°F.

On lightly floured surface, unfold and roll puff pastry to 11- by 16-inch rectangle.

Spread mustard on top, then top with prosciutto and sprinkle with 1/2 teaspoon freshly cracked pepper.

Starting with one of the short sides, roll into a log. Slice into 1/2-inch wheels and transfer to parchment-lined baking sheets, spacing at least 1 inch apart.

Bake, rotating sheets halfway through, until golden brown, 15 to 18 minutes. Let cool completely on sheets on wire racks before serving.