Preheat oven to 400 degrees Fahrenheit.  

Trim the tough ends off the asparagus, making them an equal length of approximately 8 inches. Bring a large pot of salted water to a boil over high heat.  Have a large bowl of ice water at the ready. Once boiling, add the asparagus and blanch until they are bright green and crisp tender, about 2 minutes. Drain and drop the asparagus in the ice water to stop the cooking. Once cool, drain the asparagus. Pat dry with paper towels and season with a little olive oil, salt and pepper. Set aside. 

Unroll the puff pastry onto a lightly floured piece of parchment paper. (This makes it super easy to move the pastry). Roll out the pastry to a 10X16 inch rectangle. Transfer the parchment to a baking sheet. Prick all over with a fork. Bake, checking occasionally, until the pastry is light golden brown and puffed, about 12 minutes. Remove from oven. Allow to cool slightly. Maintain oven temperature. 

Mix together the ricotta, Parmesan, egg yolk, and zest of ½ lemon until smooth. Spread the ricotta mixture over the baked pastry, leaving about a 1-inch border all around.  Lay the asparagus on top of the ricotta, alternating directions. Mix the egg white with about a splash of water. Brush the exposed pastry with the egg wash.  Drizzle the entire tart with a little extra virgin olive oil. Top with a generous amount of pepper and Parmesan; sprinkle with the toasted nuts.

Return the pastry to the oven. Bake until the asparagus is tender, and the cheeses are melted, 15-20 minutes.  Remove from oven and sprinkle with more Parmesan. Cut into squares to serve.