In a bowl mix pieces of albacore, pieces of avocado, pesto and mix. Taste and adjust pesto as per taste.
Spread butter on both sides of bread slices. Place one cheese slice on all bread slices. Add the mixture of avocado tuna melt on 3 bread slices and then cover with the other bread slice with cheese. Place this on a hot skillet and cook until golden brown , flip and cook the same on the other side as well.
Serve immediately.
Recipe by Naive Cook Cooks at https://www.naivecookcooks.com/avocado-tuna-melt/