* Drain the salmon. Remove skin and bones, if desired and break into large chunks. Set aside

* Make two sandwiches with the salmon and Gruyere cheese - without spreading the bread with butter. Season with a little salt and pepper

* Beat the egg and milk together in a shallow bowl. Dip both sides of each sandwich in this egg mixture

* Heat the butter in a large frying pan and fry both sides of the sandwiches until golden brown, when the cheese should just be starting to melt. Serve immediately