Open the tuna and discard the liquid.
Place it in a bowl followed by the spring onion, chili flakes, paprika, parsley, lemon juice, mayonnaise and salt & pepper.
Mix well until you get a thick paste.
Spread the butter on the bread slices on both sides.
Using a hotplate or a large skillet, toast the bread from both sides and set aside.
Add the tuna paste and cook it slightly until it starts to get some color.
Divide the tuna paste in half and place it onto your toasted bread.
Add the cheese slices on top and place it under a grill until it’s bubbly and starts getting some color.
Place the other slice of bread on top and cut in half.
Serve with plenty of potato crisps.