Preparation

• On a lightly floured piece of parchment paper, roll out the puff pastry into a 10×14-inch rectangle. Using a fork, prick holes all over the dough. Spread the Dijon mustard evenly over top. Arrange the ham over the dough, overlapping it slightly as needed, and leaving a 1/4-inch border on both long ends. Scatter the shredded cheese evenly over the ham, and season with freshly ground black pepper.
• Starting at a long end, roll the puff pastry into a tight log using the parchment as leverage. Press the edges together to seal. Wrap the log in plastic wrap, and refrigerate it, seam side down, for 15-30 minutes.
• Preheat the oven to 375˚F with racks in the upper and lower thirds. Line 2 large baking sheets with parchment paper.
• Using a sharp knife, cut the puff pastry log into 1/2 inch slices. Arrange the rolls on the prepared baking sheets, spacing them 1-2 inches apart. Bake until golden brown, rotating and switching the pans halfway through, about 25 minutes. Let cool slightly. Serve warm.