Rainforest has a couple dishes with Alfredo.
Brown Derby has it on their lunch menu.
Don't know how old your son is but Trattoria al Forno at the boardwalk has it on the kids menu (with Turkey Meatballs)
Don't know where you are staying, but Pop Century food court has it on the menu and probably the best place to make that kid happy is the Art of Animation food court which has a build your own pasta bar that has all the sauces. Even if you are not staying at Art of Animation, I recommend their food court for a cruise by lunch and a walk around as it is a wonderful resort to visit and see the sights. Love the cars area of that resort!