Prosciutto Palmiers

Ingredients

• 0.5 cup gruyere cheese shredded
• 3 ounces pancetta very thinly sliced
• 14 ounce puff pastry frozen thawed
• 1 tablespoon tomato paste 
• 1 teaspoon water 

Equipment

• bowl
• baking sheet
• baking paper
• oven
• knife
• wire rack
• plastic wrap
• spatula
• serrated knife
• pastry brush
• pizza cutter

Directions

1. Combine the tomato paste and water in a small bowl; set aside.Generously dust a work surface with flour.
2. Place the thawed pastry on the prepared work surface, dust the pastry lightly with flour, and, using a sharp knife or pizza cutter, trim it into a 10-by-13-inch rectangle.Using a pastry brush, coat the surface of the pastry evenly with the tomato-water mixture, using all of it. Arrange the prosciutto slices in a single layer over the tomato paste, overlapping slightly.
3. Sprinkle the cheese evenly over the prosciutto.Fold each of the long sides of the pastry in toward the center until they meet. Fold again along the center seam, as if closing a book. Wrap the roll in plastic wrap and refrigerate until firm, about 30 minutes Meanwhile, heat the oven to 400°F and arrange the racks to divide the oven into thirds. Line 2 baking sheets with parchment paper and set aside.When the pastry roll is ready, remove it from the refrigerator and discard the plastic wrap. Using a serrated knife, trim about 1/2 inch off each end.
4. Cut the roll crosswise into 1/2-inch slices. Arrange the slices on the prepared baking sheets about 1 inch apart. You should have about 12 palmiers on each sheet.
5. Bake until the palmiers are lightly browned, about 8 to 10 minutes.
6. Remove the baking sheets from the oven and flip the palmiers over with a flat spatula. Return to the oven and bake until deep golden brown, about 8 to 10 minutes more.
7. Remove the palmiers to a wire rack to cool completely. If not serving right away, store at room temperature in a container with a tightfitting lid for up to 6 hours.