Sieve flour and salt & pepper into a bowl, coarsely rub in the butter/margarine. Add sufficient water to make a soft dough. Turn onto a lightly floured board and gently knead.
Roll out pastry and use to line a swiss roll tin 28cm x 18cm / 11"x 9" with the pastry.
Place scallions, ham and cheese into the pastry. Arrange tomato slices on top.
Beat eggs and milk together and add salt & pepper. Pour gently into pastry. Sprinkle with parmesan, if used.
Bake for approx 20 minutes or until golden brown and set. Cut into slices and serve hot or cold with a green salad.