Thaw the puff pastry either by placing it in the fridge overnight or by laying it on the counter, on a piece of parchment paper, for about an hour.
Trim the ends of the Asparagus by 1 inch to get rid of the woody stalk
Once thawed unfold the flaps and slightly roll out the dough to get rid of the seems. Transfer the puff pastry dough while still on the parchment paper to a baking sheet. Sprinkle half the Gruyere and Parmesan on the puff pastry. Line the asparagus on top of the cheese. Scatter the rest of the cheese on top of the asparagus and drizzle with the olive oil. Bake for 20 minutes until the pastry dough has puffed and the asparagus is roasted and cooked through.
Sprinkle with salt, black pepper, lemon zest and juice and peas hoots before serving.
Notes
The best way to trim asparagus isn't with a knife! Simply hold it between your hands and give a gentle snap - the woody end will break right off.