Instructions

1. Preheat a frying pan over low/medium heat.
2. Drain the can of tuna fish and add it to a small bowl.
3. Add the mayonnaise, celery, onion, salt and pepper and stir together.
4. Spray one side of each slice of bread 4 times with the butter spray.
5. Add half of the tuna mixture to one slice of bread (on the not buttered side), add one slice of cheese and put one slice of bread on top.
6. Add the sandwich to the heated pan. Cook until golden brown on each side, making sure the cheese melts.
7. Repeat with the remaining ingredients.