Kneaders Copycat Tuna Melt

My friend and I went to lunch at Kneaders.  We both ordered the tuna melt.  It was so delicious that I came home and tried to recreate it at home.  Honestly, I think my version was even better because I made the tuna salad more to my liking. I have since made it many times.  I love this sandwich!  This recipe makes 2 sandwiches.

Tuna Melt
Really good wheat/seed bread
1 can albacore tuna, drained and flaked
1 dill pickle, diced fine
Mayonnaise
Sliced cheese of choice: Kneaders uses cheddar; provolone is good
Whatever else you like in your tuna salad: hard boiled egg, dill, celery, etc.  Kneaders uses a lot of dill
Soft real butter (essential)
1 avocado, smashed and salted
Thin-sliced tomato, optional
Drain and put the tuna into a bowl.  Flake with a fork.  Add the mayonnaise and pickle and whatever else you would like.  Mix well.
Heat a frying pan or a griddle.  Generously butter one side of one bread.(It is very popular these days to use mayonnaise on the outside of the bread on a grilled cheese in place of butter.  I tried it on this and it was NO WHERE NEAR as good as real butter.)  Put it butter side down in the hot pan.  Top with a generous amount of the tuna salad (1 can tuna makes 2 sandwiches.)  Put on the avocado and tomato.  Top with two slices of cheese.  Butter one side of another piece of bread and put it butter side up on the cheese.  Grill until browned.  Turn over and grill the other side until browned and the cheese is melted.  You can also make this in a panini press.