Preheat oven to 425 degrees F. Lightly flour work surface. Unfold thawed puff pastry sheet and gently roll out to 11x14-in.

Line baking sheet with parchment paper. Transfer pastry to baking sheet. Use knife to score 1-in. around the perimeter (avoid cutting all the way through). Use fork to prick the inner rectangle all over. Brush border with some of the beaten egg (reserve remaining egg for cheese mixture). Bake for 10 minutes.

In the meantime, trim approximately 1 inch off asparagus ends. Transfer to bowl and toss with olive oil until evenly coated and set aside.

In medium bowl, combine cream cheese, Gruyere, thyme, salt, garlic powder, nutmeg, lemon zest and remaining beaten egg.

Remove puff pastry from oven. Use rubber spatula to evenly spread cheese mixture inside the border. Arrange asparagus on top and sprinkle with freshly cracked black pepper to taste. Bake for 15-20 minutes.

Let cool for 10-15 minutes before serving.