Heat oven to 400 degrees. Roll out thawed puff pastry to 11 x 91/2 inches. Using a 3-inch round cutter, remove 8 rounds. Separate 1 egg; beat white and reserve yolk. Transfer rounds to a parchment-lined baking sheet and brush with egg white. Bake at 400 degrees for 12 minutes or until puffed and golden.
Fill a large, straight-sided skillet three-fourths full with water. Bring to a boil. Add asparagus and cook 1 to 2 minutes, until crisp-tender. Remove with a slotted spoon and toss in 1 tsp of the lemon juice. Season with 1/8 tsp of the salt and set aside.
In the same skillet, reduce heat until water is barely simmering. Crack 4 eggs into separate cups. Pour into water one by one. Poach eggs 3 to 4 minutes or until whites are set. Remove with a slotted spoon to a paper-towel-lined plate. Repeat with 4 more eggs.
Meanwhile, place 2 egg yolks (including the 1 reserved), remaining 2 tsp lemon juice, 1/8 tsp of the salt and the cayenne in a blender; process until combined. Melt butter in a bowl in microwave for 1 minute, covering to avoid splatter. Slowly stream melted butter into blender while running; hollandaise should thicken immediately.
To serve, place 2 puff pastry rounds on a plate. Place 2 asparagus spears and 1 poached egg on each round. Season eggs with remaining 1/8 tsp salt and pour a bit of hollandaise over each egg. Garnish with chopped parsley and freshly cracked pepper, if desired.