Makes 6 small tarts
1 sheet frozen puff pastry, thawed but still cold.
1 egg, beaten
1 1/2 cups finely grated gruyere cheese
1 pound slender asparagus
Salt and coarse ground black pepper
Extra virgin olive oil
Place a rack in the center of the oven and preheat oven to 400 degrees F. Line a baking sheet with parchment paper and set aside.
Unfold thawed puff pastry onto a lightly floured work surface. Most commercially made puff pastry sheets are sold folded into thirds. Unfold the pastry and slice into thirds at the creases. Cut each strip in half, creating six equally sized rectangles.
Gently press each rectangle with your fingers, flattening slightly. With a small pairing knife, score a 1/4 inch boarder along the inside of each rectangle. Arrange 1 inch apart on the prepared baking sheet.
Brush each square lightly with beaten egg. Sprinkle with salt and coarse ground black pepper. Top with a generous sprinkling of grated cheese. Press five to six asparagus spears into the cheese. Brush the asparagus with olive oil and sprinkle with more coarsely ground black pepper.
Bake for 20 to 25 minutes, until puff pastry is golden brown and asparagus is cooked through. Remove from the oven, allow to cool for 10 minutes before serving. Serve with thick balsamic reduction.