No reason to fight over butter or olive oil! Either of them will work, or even mix them both in. I'm from an Italian family and grew up in an Italian neighborhood in Brooklyn. My family used butter but like I said, I have seen it both ways, and I like it both ways. Olive oil of course is a bit healthier. I don't really care about tradition, I make it the way I like it. Sometimes I will throw just a bit of fresh, finely-chopped, parsley on top. Other times, I add just a small bit of sauteed garlic to the mixture. Faggettaboutit...