Being from Boston, we know alot about cod! I take cod filets (size and thickness is up to you) and cut them into serving size. I line a baking dish (like a jelly roll pan so it isn't too deep and the fish cooks bettter) with foil and spray it with one of those non-stick sprays (or you can use butter so it doesn't stick but we prefer the spray).
Take a tube of Ritz crackers and crush them finely. Melt 4 Tablespoons of butter in a pan and add the Ritz cracker crumbs. Mix it so it is a loose mixture, not all stuck together.
Bake at 350 degrees in a preheated oven.
This works for haddock also. Let me know how you like it, if you try it.