Boil the potatoes in salted water until just under cooked, allow to cool a little and peel.
Halve the bacon slices, wrap the potatoes in them, pierce a hole with a knitting needle so that the rosemary sprig can be pushed through without much effort. He should pierce the potato so that its aroma is well delivered to it.
Carefully fry the potatoes in butter and olive oil until golden and season with pepper, a little salt and a pinch of sugar.