Asparagus Puff Pastry with Boursin

0 Preheat the oven to 375 °F. Line a rimmed baking sheet with parchment paper.
1 Trim and discard the tough, woody ends from the asparagus stalks. Slice any thick stalks in half lengthwise (you can skip this step with any stalks that are too thin to slice in half). 
2 Lightly dust a countertop with flour. Roll the puff pastry out, smoothing out the folds and bumps. It should be about a 10x12 rectangle. Transfer the pastry to the prepared baking sheet.
3 Use a fork to pierce the surface of the dough all over (this will help it to bake evenly). Using a sharp knife, score the puff pastry all around the sides, about 1-inch from the edges. Don’t cut the pastry all the way through, just score it about halfway through the layers to create a border.
4 Whisk together the egg and 1 tablespoon of water. Brush the border of the puff pastry with egg wash.
5 Spread the Boursin out evenly over the center of the pastry. Top the Boursin with salt, lemon zest, black pepper, and cheese. Spread the asparagus out on top of the Boursin in an even layer.
6 Bake the pastry until the edges are golden brown and crisp, 28 to 32 minutes. Let it cool slightly before slicing.