Cheese & Onion Pasty/Cornish Pies

"The traditional Cornish recipe uses a cheese such as Double Gloucester or English Cheddar, but I have made some very tasty varieties using Stilton, Feta, Bleu Cheese, and even Havarti."

Ingredients
3 sheets ( I use frozen, but homemade is fine if you are a purist)
3/4 ounce unsalted butter
3 medium onions, finely chopped
3/4 lb double Gloucester cheese or 3/4 lb cheddar cheese, grated
6 tablespoons fresh parsley, chopped

Directions
Thaw the pastry.
If using homemade, put your dough in the refrigerator to chill.
Preheat oven to 400°F.
Melt the butter in a frying pan on a low heat.
Mix in the onions and cook them until they are just beginning to soften.
Mix them with the cheese and parsley.
Roll out the pastry and cut out 6 rounds, each about 6 inches in diameter.
Put a quarter of the cheese mixture on one half of each one.
Fold over the other side and crimp the edges together.
Lay the pasties on a floured baking sheet and brush them with milk or beaten egg.
Bake them for 30 minutes and serve hot.