Given you need to worry about allergies, the best restaurants I've seen for dealing with them anywhere are the Disney restaurants. When you tell your server someone with allergies is dining, the chef will come out and discuss your issue and tell you exactly what he can prepare for you. I've never seen anything quite like it.

There is a real Italian restaurant in Celebration Florida in their town center. It was pretty authentic and the food tasty. I believe it's called Angelina's. They should be able to accommodate a family group, though since the owners are Italian, they may be closed on Christmas day.