Preheat oven to 400°F.
Sprinkle the counter or wood cutting board with flour.
Roll out the thawed puff pastry into a 16-by-10 inch rectangle. It does not have to be perfect!
Cover a baking sheet with parchment paper and place the puff pastry on it.
With a sharp knife, lightly score the pastry dough 1 inch in from the edges. Do not cut all the way through the dough.
Pierce the dough inside the border with a fork about every inch.
Bake until light golden brown, about 10 minutes.
Stir together the ricotta, egg, parsley, lemon juice, cayenne, salt and pepper.
Spread the ricotta mixture on the inside of the border of the pastry.
Sprinkle the Gruyère on top of the ricotta.
Trim the ends of the asparagus so that they are all about the same size and fit inside the pastry. Place the asparagus spears inside the tart shell. Alternate the tips and bottoms so that they fit better.
Brush the asparagus with olive oil and season with salt and pepper.
Bake until the spears are tender, about 20 to 25 minutes. Enjoy warm or at room temperature.