Heat the butter and sauté the leeks until soft. Fry the bacon in a little olive oil until crisp. Mix together the cream, a third of the Parmesan and eggs, set aside. Add some of the mixture to the bacon and leeks, add the parsley and mix well.
Pile the bacon, leek, parsley and cream mixture into the pastry case. Top with the rest of the egg, cream and cheese, the remaining parmesan, and bake at 180c for 30 minutes.