I don't do Polish at all, but: The pictures I see of chleb tostowy pszenny do look right. (We just call that "bread" in the US. It's inexpensive, and we tend to have some in every kitchen. Ours is probably much sweeter but that doesn't matter.)

With that bread: Make a plain cheese sandwich with whatever melty cheese you enjoy. Then put butter on the outside (on both sides of the sandwich) using whatever butter you like.

Put that buttered cheese sandwich in a frying pan (patelnia uniwersalna) at ~medium heat.

Do not walk away from it. Flip it over every now and then to cook it evenly and see how it is doing.

When the cheese gets all melted and goopy at about the same time that the bread changes color and becomes toasted, then you did it right. Cut it in half and eat it.

If you didn't do it right, then that's fine too. Cut it in half and eat it anyway.

(Repeat regularly until perfection is reached. You'll know it when you find it.)