The rolls should be served warm, so reheat them in batches as platters need replenishing.

　　

Ingredients

Makes about 96 hors d'oeuvres

　　1 (17 1/4-ounce) package frozen puff pastry sheets, thawed

　　2 large egg yolks, lightly beaten with 2 tablespoons cold water

　　5 ounce finely grated Parmigiano-Reggiano (1 3/4 cups packed)

　　28 (3/4-inch-thick) asparagus (2 pounds), stalks trimmed to 6-inch lengths and tips reserved if desired

　　3 tablespoons white or black truffle oil (1 1/2 ounces; optional)

　　

Step 1

Unfold pastry sheets and halve each parallel to fold lines. Roll out 1 half (keep remaining 3 halves chilled, covered with plastic wrap) into a 20- by 7-inch rectangle with a floured rolling pin on a well-floured surface. (Pastry will shrink slightly after rolling.) Brush off excess flour from work surface and both sides of pastry, then trim all edges with a sharp knife to make even. Cut crosswise into 6 (6 1/2- by 3-inch) rectangles.

　　

Step 2

Brush rectangles with some egg wash and sprinkle each evenly with 1 packed tablespoon cheese, leaving a 1/2-inch border on long sides. Lay an asparagus stalk along 1 long side, then roll up asparagus in pastry, pressing seam to seal. Make more rolls with remaining pastry, cheese, and asparagus.

　　

Step 3

Arrange rolls, seam sides down, about 1 inch apart on lightly oiled baking sheets and brush top and sides lightly with egg wash. Chill rolls until pastry is firm, at least 15 minutes.

　　

Step 4

Preheat oven to 400°F.

　　

Step 5

Bake rolls in batches in middle of oven until puffed and golden, about 16 minutes.

　　

Step 6

Transfer with a metal spatula to a cutting board and trim about 1/2 inch from ends. Halve each roll crosswise, then, starting about 1/2 inch from either end, cut each section diagonally in half (see photo, opposite). Stand asparagus rolls on end, 2 by 2 on platters, and drizzle each with 1 drop of truffle oil (if using). Serve warm.