a hash or stew
Not necessarily something 'roasted'—in fact it can mean just about everything else. In Lombardy, it's a dish of onions, pork and sausage, served with polenta (sometimes called a rostida); in Milan it's called rostisciada.
In the eastern Alps, it can mean gröstl (meat and potato hash). Elsewhere it can be any kind of stewed meat or hash.
Patate rosticciate, though, will probably really mean roast potatoes.