Preheat oven to 220 C with grill function ON.
Line baking tray with baking paper.
Grate entire bar of chocolate into fine parmesan-like crumbs.
Put pineapple slices on paper (no syrup!). Sprinkle each with grated chocolate.
Shoot into oven and carefully observe the chocolate melt. After few minutes the sugar in it will begin to caramelize and burn. This is the moment you want to take it out and serve. Mm, impressive, fast and tasty!