Creating the Sheet-Pan Asparagus & Gruyère Tart is simple if you follow these steps:

1. Preheat Oven: Preheat your oven to 400°F (200°C).
2. Prepare Baking Sheet: Line a baking sheet with parchment paper.
3. Roll Out Puff Pastry: Unroll the puff pastry on a lightly floured surface. Transfer it to the prepared baking sheet, pressing it gently to fit.
4. Score the Edges: Using a sharp knife, score a 1-inch border around the edges of the pastry. Be careful not to cut all the way through.
5. Prick the Center: Use a fork to prick the center of the pastry within the scored border. This will prevent it from puffing up too much while baking.
6. Add Cheese: Sprinkle the shredded Gruyère cheese evenly over the pastry, avoiding the edges.
7. Arrange Asparagus: Neatly arrange the trimmed asparagus on top of the cheese.
8. Prepare Egg Wash: In a small bowl, whisk together the egg and milk. Brush the mixture along the edges of the pastry.
9. Season: Drizzle the asparagus with olive oil and season with salt, pepper, and lemon zest (if using).
10. Bake: Place the baking sheet in the preheated oven and bake for 25-30 minutes or until the pastry is golden brown and the cheese is bubbly.
11. Cool Slightly: Remove from the oven and let it cool for a few minutes before slicing.

By following these steps, you’ll create an incredible Sheet-Pan Asparagus & Gruyère Tart that will wow your family and friends!