Preheat
the oven to 400°F/200°C/gas 6. Butter a baking sheet.
Trim the tough bottom parts off the asparagus. Cook in
salted, boiling water for 5-10 minutes, or until
crunchy-tender. Drain and chop coarsely.
Sauté the asparagus in the butter in a large frying pan
over medium heat for 5 minutes. Season with salt and
pepper.
Unfold or unroll the pastry into a rectangle
(reserve a little to decorate).
Place the asparagus in the center with the cheese and
parsley.
Brush the edges of the pastry with the egg yolk. Fold
the pastry over the filling, pressing the edges to seal.
Place on the ,baking sheet seam-side down. Brush with
the remaining egg yolk and decorate with the reserved
pastry.
Bake for
25-30
minutes, or until golden.
Serve warm.