Preheat the oven to 400°F. Line a baking sheet with parchment paper.
In a mixing bowl, combine the softened cream cheese, grated Parmesan cheese, garlic powder, lemon zest, salt, and pepper. Mix until smooth and well combined.
Roll out the thawed puff pastry on a lightly floured surface. Cut the pastry into rectangles, about 4 inches by 6 inches.
Place a small spoonful of the cream cheese mixture in the center of each pastry rectangle. Lay 2-3 asparagus spears on top of the mixture.
Fold the edges of the pastry over the asparagus and cream cheese filling, pinching to seal. Place the bundles seam-side down on the prepared baking sheet.
Brush the tops of the bundles with the beaten egg and sprinkle with sesame seeds if desired.
Bake in the preheated oven for 20-25 minutes, or until the pastry is golden brown and puffed.
Remove from the oven and let cool slightly before serving.