When I first saw the movie ET in a Florentine theater back in the early 80s, the Halloween scene with all the kids running around in costume fascinated my Italian friends. It wouldn't today, because the holiday is beginning to catch on, though as a distinctly adult affair that gives grownups a chance to dress up and party -- in short, as a second Carnevale.
Other than some of the costumes (a bare-chested pair of demons, male and female, come to mind….), there's no connection between the Italian celebration of Halloween and the more dread traditions of northern Europe, which derive from Samain, the last night of the Celtic year, in which the worlds of the quick and the dead merge, allowing the shades to wander the land and greatly increasing the powers of devils and other evil spirits.
The Roman analog of the Celtic Samain was the Feralia, held on February 21 to honor the dead and give peace to the departed. It was a family (as opposed to state) festival, with quite a number of dead to honor, including the Genii, the family's male ancestors, and the Lares, who were spirits of good people. There was also another class of spirits to deal with: Lemuri and Larvi, the malicious ghosts of those who had been evil in life, and here the big problem was getting them out of the house before they could cause illness or other mischief. To do so the Pater Familias would arise in the middle of the night and wander about the house barefoot, his mouth full of black fava beans that he would toss one by one over his shoulder onto the floor. The Lemuri were supposed to stoop to gather them, and then leave the house.
This sort of custom obviously didn't sit well with the early Church; Roman Christians had already begun to observe the Antiochean custom of venerating the Martyrs on the first Sunday after Pentacost, and in 609 Pope Boniface III formally recognized the observance, establishing All Saints Day, which he decreed should take place on May 13. This had been the day the Pagan Romans had venerated their Pantheon, so Pope Boniface was replacing a Pagan holiday with a Christian one, and since All Saints Day by extension celebrated the dead, it also took care of the Roman Feralia. However, it did nothing about the celebration of Samain in the more northern sections of Europe.
To address this problem, in 835 Pope Gregory IV moved All Saints Day to November 1 -- the day after Samain, and in the X century the Church dedicated November 2 to the remembrance of the dead. As a result, Italians now celebrate the saints on November 1st and remember their dead on the 2nd, which is Memorial Day.
One vestige of the old Roman pagan tradition survived, however: fave dolci, sweet fava beans, also known as ossa dei morti, the bones of the dead. There are a number of recipes from throughout the Peninsula; perhaps the most interesting is Pellegrino Artusi's from La Scienza in Cucina e l'Arte di Mangiar Bene (the Italian equivalent of Fannie Farmer). Artusi was keen on instructing his readers and clearly thought most of them no longer knew why they were making these cookies. Just that it was a part of fall, rather like chestnuts or new wine.
Artusi's commentary and recipes.