Anatolio Henin of Milan, working from 1866, when he assumed the workshop of Luigi Henin. As the device in the mark suggests, Henin was a large manufacturer of flatware. Unfortunately, it doesn't help narrow the date any; A. Henin existed well into the 20th century, working throughout the Monarchy and into the Fascist period. (They were assigned registry number 42 MI in 1935.) Still, I think your spoon probably dates from the 19th rather than the 20th century. Hope this helps!