Pre-heat oven to 375 F (180 C).
Spread butter evenly on each slice of toast.
Optional: spread a thin layer of mayonnaise on top.
Drain pineapples, let drip in a sieve.
Place on top the ham, followed by the pineapple and at last a slice of cheese.
Use parchment paper on the oven rack and place the toast directly onto the paper.
In a few minutes the cheese will melt and it will get brown.
When you see that the cheese has melted into the pineapple opening and gets brown, you should remove the toast right away. It will be after about 6 minutes.
Let cool off a bit before you enjoy this delicious snack.