Around the HQ, we stick with the un-Yankee, Southern Italian/Sicilian Christmas Eve fast, which means seafood. In past years, I have had the real 7 Fishes with fried baccala, steamed mussels, scungilli, etc etc. A wonderful fish feast which it would be a stretch to term "fasting." The Catholics are very clever with their concept of fasting.
The best-known Sicilian Primi is Pasta Con Sardi - pasta with anchovies (ie small sardines) - what I term Pasta With Minnows aka Pasta with Bait.
What is an "anchovy"? Never, ever use those tinned brown over-salted anchovies that they put on cheap pizzas. Disgusting stuff, cat food for a cat you hate. If you can't get fresh anchovies (they are white) at your local fish market, use the canned white anchovies in olive oil. Tasty. Good Italian markets have good fresh or oiled white anchovy filets.
Here's the recipe. Yes, to be authentic it needs the breadcrumbs. And here's another Vigilia favorite: Fried Baccala Balls. I've also had these with mashed potato in the cod mix to hold it all together. Nothing is more delicious.
Traditionally, you have to have Struffoli for dessert even though I find it inedible.
Truth is, in recent years we just make poached salmon with yogurt-dill sauce, to be ready to serve at room temp. after getting home from church.