Ham, Gruyere and Dijon Palmiers

Ingredients
1 sheet (about 9 ounces) frozen puff pastry, thawed
2 tablespoons Dijon mustard
1 cup (3 ounces) shredded aged Gruyere (or Swiss) cheese
1/4 cup (1/2 ounce) freshly and finely grated Parmigiano Reggiano cheese
4 ounces very thinly sliced good-quality baked ham

Instructions
1.Position sheet of pastry on a lightly floured surface so that a short side is closest to you. Roll into a 10-by-14-inch rectangle.

2.Spread mustard over pastry. Distribute cheeses evenly over surface. Arrange ham in a single even layer, cutting to fit. Lay parchment paper or wax paper on top and gently compress layers with a rolling pin. Peel off paper.

3.Cut rectangle in half to make two 10x7-inch bands. Roll one long edge of one of the bands into the center; roll the opposite edge in so the two rolls meet in the middle and resemble a double scroll. Press lightly so the rolls stick together (spread a few drops of water where the two rolls meet to help them stick, if you need to). Repeat with the second band. Wrap in plastic and chill until firm, at least 1 hour in the refrigerator or 30 minutes in the freezer.

4.Preheat oven to 425F and line two baking sheets with parchment paper. With a very sharp knife, slice each roll into 24 pieces. Place on baking sheets at least 1 inch apart. Bake 10 to 12 minutes, until pastry is flaky. Serve warm or within the hour, if possible.