Heat oven to 400 F.
Meanwhile, bring a sheet of puff pastry to room temperature. Gently unfold or roll out the dough and, using a sharp knife, score it about 1 inch from the edge, making a rectangle all the way around. This will be the “crust” once the pastry bakes.
Inside the rectangle, pierce the dough every ½ inch or so to prevent bubbles.
Bake the dough at 400 F for 15 minutes.
Sprinkle the baked pastry with 1-2 cups of shredded Gruyère.
Lay full asparagus spears on top of the cheese and brush with olive oil.
Sprinkle with salt and pepper to taste.
Bake at 400 F for 20 minutes and serve.