Preheat the oven to 175 degrees.
Melt the butter in a frying pan.
Add and fry the leek for 2-3 minutes. Add the broccoli and sauté for another 5 minutes, stir.
Add the remaining ingredients in the frying pan apart from the chives and the parsley. Cook over a medium heat until the cheese has melted completely (stir frequently so that the cheese does not stick to the bottom of the pan). Add the chives and the parsley and salt and pepper to taste. Move to one side.
Butter an oven tray and sprinkle with flour. Open the puff pastry and spread it on the tin, place the filling on top and cover it with the second pastry sheet making sure that the surface is sealed.
With a brush cover the pastry surface with the beaten egg. Bake at 175 degrees for 25-30 minutes until the pie’s top becomes golden brown.