1. Heat oven to 400 degrees F. Beat egg and water in bowl.
2. Unfold pastry on lightly floured surface. Roll into 14" square. Place cheese in center. Fold pastry up over cheese to cover. Trim excess pastry and press to seal. Brush seam with egg mixture. Place seam-side down onto baking sheet. Brush with egg mixture.
3. Bake for 25 minutes or until the pastry is golden brown. Let stand for 20 minutes.